Good timing, perhaps. ActiveMerchant 1.0.0 was just announced, with a home page here:
http://www.activemerchant.org/
At that page, there's a link, Discussion, to a Google group. I'd ask questions there.
Regards, Craig
wow! great news.
There's also this tutorial published earlier in the year, http://www.omninerd.com/2007/01/23/articles/66
Jodi