That took me forever to figure out. I had the led flashlight app when I initially updated to 2.2 (stock unrooted) but uninstalled it and went through numerous reboots. The camera would occasionally work, but it was hard to troubleshoot because it was so intermittent.
Finally, yesterday I tried to use the barcode scanner to scan some qr codes. When it couldn't access the camera it got me thinking about a couple of 3rd party barcode apps that I had installed. Uninstalled those, rebooted, and no issues yet.
Figured I'd share that since I haven't seen anyone else mention that, and a non-working camera (especially with how great the evo camera is!) sucks.
thanks,
will