I now use Vagrant for App Engine and it's a breeze to set up. Since the working directory is mounted by the vm textmate works as always. I only have to ssh into the virtual machine to run some python scripts since locally there are some dependencies issues.

That's cool if you're happy with OS X. It's just that I know many OS X devs who use ubuntu in a VM. I'm personally happy with a full install of Ubuntu and Emacs instead of textmate while others prefer OS X + textmate or emacs or vim or what have you, to each his/her own. I was just stating an alternative, I didn't know that was trolling.

I hear you: TextMate is a great editor, especially when you want to browse through a lot of code. That said, "e" on Windows is fairly TextMate compatible (at least it runs the TextMate plugins). For Ubuntu, GEdit and Emacs are very good. Emacs with Speedbar lets you whip through lots of code quickly. GEdit also provides good plugins and multiple directory code browsing.

All that said, I still boot OS X for specific apps (TexShop, OmniGraffle mostly). Anyway, it is a free world, and certainly OS X is a great choice for development.