I went for the 50D when my XT died for the second time this year. That would have been $400 in repair bills this year, and more than the XT was worth on the used market.
If you go for the 50D, you can hang on to it for, say, six months, and then sell it for roughly what you paid for it, and at that point, the 7D will be readily available and might even have come down a little in price. Getting the 7D right now is to get it at its most expensive and difficult to find; it's the hot new toy. And the majority of the 7D features are geared for fast action shooters, which doesn't necessarily sound like something you need.
There's also the fact that a 60D is likely to be announced in March, at the ($500 lower) XXD price point, probably incorporating some of the 7D new features (my bet is the LCD overlay in the viewfinder and some form of HD video) and very likely the same sensor with some tweaks.
For me, I'm thinking of my refurb 50D more as a stop-gap, or a camera-on-trial rather than a permanent purchase. It's all going to depend on how much I like the interchangeable focus screen feature and whether it survives into the next generation of camera bodies.
