Well, the Sony Alpha already out on shelves, and is getting mediocre reviews. We all know its sensor isn't anywhere nearly as clean as the 350D, but then what surprised everyone is that it's also noisier than the Nikon D200. (The D200 supposedly uses the same sensor as the Alpha.)
Its sensor dust removal feature wasn't working well, and Image Stabilization doesn't show on the view finder.
The 10.2 MP Nikon will be interesting. It's probably the Nikon D70 replacement. The 350D successor will be interesting to see also. Neither of these camera can be better than their big brothers (Nikon D200 and Canon 30D), however. So chances are we'll see only minor enhancements like larger LCD screen, more comfortable grips, etc.
I doubt the price for the 350D will drop further, as it's already very cheap compared to the debut price. The 350D successor will likely cost $300 more when it comes out, so there's still a lot of reasons to buy the 350D.
If you need the camera now, then buy it, and I'm sure you can ebay it for 90% of the value if you decide to switch later. If not wait a few months.