Uh, not borderline, friend. Posting announcements like this on elance.com and the like would most definitely be spam, and most definitely unwelcome.
Why not announce to various blogs and tech-news aggregators? TechCrunch, TechMeme, Slashdot, Webware, AppScout might all be good places to announce a new app.
Buy an ad on Facebook. Start a group on facebook. Get your friends to sign up and promise to invite at least 2 other friends that don't know anyone else already signed up.
But don't, under any circumstances, post your announcement where it will be OT - that's what makes the internet suck.
