HTC releases HTC Vision (T-Mobile G2) source code - HTC Source
Just like they have done in the past with all their previous Android handsets, HTC has released the source code for the HTC Vision (T-Mobile G2). For now, there’s not much that can be done with the code since the G2 still does not have a permanent root solutions. Developers may be able to use the code to gain some addition insight as to how the device is actually locked down, but unfortunately there’s no guarantee.
If you’d like to take a peek at the T-Mobile G2’s source code, you can find it here. Typically HTC does a really good job of posting the correct links up on the Developers page, but as of right now the G2 source is still missing and the HTC Desire Z link is pointing to the wrong file.