This is copied from another forum. I would welcome any comments:
The DESIRE only works on 54G or 11B. It will see a N series router but wont connect to it. As a lot of WIFI hotspots are upgrading to the later N series, you're stuffed. If your on Virgin M, and have 50 meg you will have N series router - so another problem.
HTC wont give a straight answer, but say the problem may be resolved with Andriod 2.2 but will not say if the WIFI chipset in the handset will support N type WIFI.