that's amazing news. It's also a great business decision. It does absolutely nothing negative and gives them a lot higher appeal to folks that enjoy tweaking their phone to get the most out of it. Kudos HTC, hope the other manufacturers follow suit
HTC was required by an agreement to release the kernel source, this was not an option for them to do. They were actually not in compliance after the release of the TB, as the source was supposed to be released by the time the phone was available.
The way I understood it was that they had 90 days from the release date to release the source code. That could be wrong though so please correct me if it is.