This week’s Windows Mobile 6 announcement kicked off the latest round of ‘Will they or won’t they provide upgrades?’ A post on the XDA-Developers forums suggests that HTC will not release WM6 upgrades for current devices. This includes fairly recent devices; instead, HTC recommends that you look at their new lineup.
On the other hand, one HTC device, the T-Mobile Dash (HTC Excalibur), is already scheduled to receive a Windows Mobile 6 upgrade. I suspect that it will be up to the company branding the HTC-devices to decide whether or not to issue upgrades.