I'm still on my first body, but when I upgrade in the near future, I plan on keeping my T1i as back-up/wife camera. I'm waiting to see what the 1D mk 4 goes for once the 1Dx comes out, otherwise I'll likely get the 7D.
There are countless people in my neck of the woods that try to sell their old XS, XT and XTi's for between $6-700. Newer Rebels are always on sale and I hope people are smarter than that. I'd feel bad if I sold my T1i for that much.