I didn't really like the gameplay of the end fight in Portal: Prelude, and there were a couple glitches, but I still recommend the game. I do think it played out pretty well, story-wise. The rest of the end level was good, and there was a visit from some old friends from HL2, slightly enhanced with Portal-style playfulness.

Anyway, go get it!

Speaking of Portal, here's a funny video of some turrets talking.

edit: Here's a neat song summarizing the plot of Portal. Spoiler, obviously. How would one classify this, musically?

edit: Added strikethroughs because YouTube is showing commercials now.