I know this is probably a bit late, but I noticed the link to one of the articles from the haijinx archives.
Quoting myself ("A Lost Introduction")
Indeed, clarifying this split between haiku and senryû is one of the primary goals of haijinx. The "hai" in haiku is "playful" or "humorous" and we wish to highlight this particular feature. There is simply no hai in haiku without some sense of humor, lightness, or playfulness. We are not alone in this belief. Famed translator R.H. Blyth, in Haiku, Volume One: Eastern Culture (The Hokuseido Press, Tokyo, 1949), defines several key characteristics of haiku. Humor is first on that list. Akito Arima, the past president of the Haiku International Association, writes in the preface to A Hidden Pond (Kadokawa Shoten, Japan, 1997) that "[t]he universal character of haiku may be due to the fact that they always contain a sense of humor, as well as scenes of nature and daily life, things appreciated by anybody." This list of primarily Japanese experts could go on.
— Mark Brooks, A Lost Introduction
http://www.haijinx.org/quarterly/a-lost-introduction/
haijinx IV:1 includes Frank Dullaghan's new article, "Humour, Life and Haiku"
http://www.haijinx.org/IV-1/articles/dullaghan.humour.html
And while there have not been many recent articles on hai, humor and haiku in haijinx, the archive boasts the thoughts of several poets on the topic.
haijinx I:1 (Spring 2001)
Susumu Takiguchi — Sense of Humour: The Forgotten Prerequisite of Haiku
http://www.haijinx.org/I-1/articles/takiguchi.html
Nobuyuki Yuasa — Laughter in Japanese Haiku (reprint)
http://www.haijinx.org/I-1/articles/yuasa-p1.html
Wiliam J Higginson — Humor in Bashô's Hokku I: The Childlike
http://www.haijinx.org/I-1/articles/higginson.html
Serge Tomé — Humour in the Western Haiku
http://www.haijinx.org/I-1/articles/tome-p1.html
Michael Dylan Welch — The Difference Between Haiku and Senryu
http://www.haijinx.org/I-1/articles/welch.html
John Crook — Humour in Haiku
http://www.haijinx.org/I-1/crook/index.html
Ikuyo Yoshimura — haiku with humour
http://www.haijinx.org/I-1/yoshimura/index.html
haijinx I:2 (Summer 2001)
Wiliam J Higginson — Humor in Bashô's Hokku II: Playing in the Tradition
http://www.haijinx.org/I-2/articles/higginson.html
David G Lanoue — Issa's Comic Vision
http://www.haijinx.org/I-2/articles/lanoue.html
Ryu Yotsuya — Humor and Kusatao's Haiku
http://www.haijinx.org/I-2/articles/yotsuya.eng.html
Randy Brooks — Consonance as the Genesis of Humor in Haiku
http://www.haijinx.org/I-2/brooks/index.html
David Cobb — Humour in Haiku
http://www.haijinx.org/I-2/cobb/index.html
Dhugal Lindsay — Humour in Haijin
http://www.haijinx.org/I-2/lindsay/index.html
haijinx II:1 (Spring 2002)
Patrick Gallagher — Tell About the Truth As If It Were False
http://www.haijinx.org/II-1/articles/gallagher.html
Wiliam J Higginson — Humor in Bashô's Hokku III: Cosmic Humor
http://www.haijinx.org/II-1/articles/higginson.html
Janice Bostok — To Laugh Or To Cry
http://www.haijinx.org/II-1/bostok/index.html
Peggy Willis Lyles — What's So Funny?
http://www.haijinx.org/II-1/lyles/index.html
Quoting myself ("A Lost Introduction")
Indeed, clarifying this split between haiku and senryû is one of the primary goals of haijinx. The "hai" in haiku is "playful" or "humorous" and we wish to highlight this particular feature. There is simply no hai in haiku without some sense of humor, lightness, or playfulness. We are not alone in this belief. Famed translator R.H. Blyth, in Haiku, Volume One: Eastern Culture (The Hokuseido Press, Tokyo, 1949), defines several key characteristics of haiku. Humor is first on that list. Akito Arima, the past president of the Haiku International Association, writes in the preface to A Hidden Pond (Kadokawa Shoten, Japan, 1997) that "[t]he universal character of haiku may be due to the fact that they always contain a sense of humor, as well as scenes of nature and daily life, things appreciated by anybody." This list of primarily Japanese experts could go on.
— Mark Brooks, A Lost Introduction
http://www.haijinx.org/quarterly/a-lost-introduction/
haijinx IV:1 includes Frank Dullaghan's new article, "Humour, Life and Haiku"
http://www.haijinx.org/IV-1/articles/dullaghan.humour.html
And while there have not been many recent articles on hai, humor and haiku in haijinx, the archive boasts the thoughts of several poets on the topic.
haijinx I:1 (Spring 2001)
Susumu Takiguchi — Sense of Humour: The Forgotten Prerequisite of Haiku
http://www.haijinx.org/I-1/articles/takiguchi.html
Nobuyuki Yuasa — Laughter in Japanese Haiku (reprint)
http://www.haijinx.org/I-1/articles/yuasa-p1.html
Wiliam J Higginson — Humor in Bashô's Hokku I: The Childlike
http://www.haijinx.org/I-1/articles/higginson.html
Serge Tomé — Humour in the Western Haiku
http://www.haijinx.org/I-1/articles/tome-p1.html
Michael Dylan Welch — The Difference Between Haiku and Senryu
http://www.haijinx.org/I-1/articles/welch.html
John Crook — Humour in Haiku
http://www.haijinx.org/I-1/crook/index.html
Ikuyo Yoshimura — haiku with humour
http://www.haijinx.org/I-1/yoshimura/index.html
haijinx I:2 (Summer 2001)
Wiliam J Higginson — Humor in Bashô's Hokku II: Playing in the Tradition
http://www.haijinx.org/I-2/articles/higginson.html
David G Lanoue — Issa's Comic Vision
http://www.haijinx.org/I-2/articles/lanoue.html
Ryu Yotsuya — Humor and Kusatao's Haiku
http://www.haijinx.org/I-2/articles/yotsuya.eng.html
Randy Brooks — Consonance as the Genesis of Humor in Haiku
http://www.haijinx.org/I-2/brooks/index.html
David Cobb — Humour in Haiku
http://www.haijinx.org/I-2/cobb/index.html
Dhugal Lindsay — Humour in Haijin
http://www.haijinx.org/I-2/lindsay/index.html
haijinx II:1 (Spring 2002)
Patrick Gallagher — Tell About the Truth As If It Were False
http://www.haijinx.org/II-1/articles/gallagher.html
Wiliam J Higginson — Humor in Bashô's Hokku III: Cosmic Humor
http://www.haijinx.org/II-1/articles/higginson.html
Janice Bostok — To Laugh Or To Cry
http://www.haijinx.org/II-1/bostok/index.html
Peggy Willis Lyles — What's So Funny?
http://www.haijinx.org/II-1/lyles/index.html