LD25, here I come!
Unfortunately I couldn’t enter #24, but I’m here to redeem myself for #25.
I’ve been rockin’ the C# for a while now so I’ll probably use that. I may also get scared and fall back to trusty old C/C++ 
The gimp will be preparing my art.
Sfxr, Audio Sauna and Audacity will do the sound.
If I stick with C#, I’ll use OpenTK, otherwise I’ll fall back to what I used last time, which is the Angel2D / C++ combo.
Angel2D is actually a pretty cool little engine that is specifically designed for game jams. It has Lua scripting, basic AI pathing and Box2D physics built in ready to go. For any C++ers out there that are not sure where to start, give it a look at http://code.google.com/p/angel-engine/
It supports Windows, Linux, OSX, iOS and has support Xbox360 controllers.
Anyway, good luck everyone, hope you all produce something you will be proud of.