A handful of Treo resources: Treo Central (info & store); Treo 600 World (news & store); Handango - Palm Software (software review and purchase); MobileWhack Palm (reviews and links); and TreoMB (news, reviews, & message boards).
Perhaps you and Dinah (who also recently got a Treo 600) should share experiences!
Check it out: http://www.metagrrrl.com/metagrrrl/2004/01/treo_600_tips.html
Sprint Treo 600 Updater 1.10, in case they're your provider:
http://support.handspring.com/esupport/forms/hsResolutionView.jsp?ResolutionId=9589&lstProducts=4442 (of course, cross-posted on Dinah's site).
I have loaded the update to the Sprint Treo 600 and have noticed improved Web browsing, but SMS is not turned on in this area yet.