As if I didn't already have enough going on this week, I just did this:
Parts were approximately $60, using the PS3 replacement drive assembly and other recommended items from various how-tos on the Internet. Essentially, the diode is removed from the disc assembly, installed in an old 5mw red laser housing, and connected to a brand new LM317 based power supply. I am well on my way to building an adorable little blue laser pointer for far under $100. It is really more purple than blue, but it looks pretty cool. Right now I'm still too afraid to crank up the juice to see how bright it can get.
According to some random forum post:
lasing threshold: 27-28ma
working current/voltage: 4.4v @ 30-40ma
I can at least verify the lasing threshold was accurate--I do not have the appropriate equipment to measure power output.
And of course, I couldn't have done it without information from Sam's Laser FAQ, specifically the article examining Blu-Ray Laser Diodes.