On the heels of the HTC S620 Windows Mobile 6 upgrade comes the one for the HTC X7500 Advantage (The upgrade does not apply to the HTX X7501).
The download is free from the HTC e-Club (membership required) and you must register your X7500 to be able to download the upgrade. One you have registered your device, it will appear in the Phone Software Updates section.
The update will replace the current ROM image and will erase partnership and all user data and programs on your device. Be sure to back everything up before you start.
Unless I’ve missed it somewhere along the line, the only outstanding Windows Mobile 6 upgrade promised by HTC is the one for the HTC P3300.