I have the T1i, too. The reason for me not to upgrade was the almost not noticable increase in image quality. Of course, the 7D is faster, better weather sealed, has the better viewfinder and the better handling - but the image quality isn't really noticably better. That's why I prefer to stay with the T1i until there's a camera that's offering better image quality - at least in JPG. I improved my T1i's handling by getting a battery grip and it feels OK.
In the time between I just got some better lenses like the great 100-400mm (very nice for wildlife) and the 100mm 2.8L IS USM for macro, portraits (instead of a 70-200mm 2.8 - I don't have the zoom but all the other features and the macro possibility for a lower price)
and "lower" light.
I'm quite happy with my solution. Feels better than buying a new camera that has the same image quality now and if they release something better you pay twice if you want that, too. At least I have some great lenses now and if they release a better camera (to be expected until september + some time until the price isn't the "new equipment price" any more) I'm prepared.
(OK, the 5D3 comes first - the improved crop frame camera follows (much?) later.)