I know you are working heavily on the project drawer and may know this, but FYI ...
Bug: TextMate does not consistently move files (on the hard disk) as they are moved in the project drawer. Reproduce: Set up a project with several existing files added from a directory, lets say ~/Sites/lib/php/report . they are not grouped in the project drawer, just loose. Then, in the project drawer there is a group called unit_tests, which exists on disk as ~/Sites/unit_tests. I have a file named settings.ini that is from the reports directory but not grouped anywhere in the project drawer. I like to alphabetize my list of files so I can easily find them later, which means dragging the files into place manually. in doing so, say I accidentally move settings.ini file into the group unit_tests. What happens is that TextMate physically moves settings.ini into ~/Sites/unit_tests. Back in the project drawer when I notice the mistake, I move it out of the unit_tests group but TextMate does not physically move the file out of ~/Sites/unit_tests back into ~/Sites/lib/php/reports, like it should. This confuses TextMate (and me) and when i repopen a project, the files are back in unit_tests.
aside from that ... what about the ability to set a root directory for the project drawer so the project drawer can be an instance of the mac os x finder in list mode? Maybe you could have several roots if your project contained files scattered around the hard disk (which doesn't seem like a typical scenario to me).
if nothing else, I would like to have the option to alphabetize the project drawer. This would just make dealing with large amounts of files easier.
in any event the project drawer is still very useful in its current state.
thanks, Kumar