Steps to reproduce:
1) Go to https://minecraft.net/download and download Minecraft for OSX (launcher v1.6.44 at the time)
2) Mount minecraft.dmg and drag minecraft.app to applications folder alias (nice install folder art, guys!)
3) Launch minecraft.app via application folder, applications smart folder, or Alfred
4) (sometimes happens) minecraft.app updates itself
5) minecraft launcher frame loads, but launcher itself is a white screen. Within a few seconds the cursor becomes a beachball. App is frozen, and once it loses focus, it never comes back (IE, when you switch active applications from say, Chrome and back).
6) After heartbreaking moment when you thought app would work, force quit it via cmd + opt + esc. No actual crash, no error report, nothing.
7) Try again repeatedly while kvetching on twitter.

I've tried:
• redownloading the launcher/reinstalling multiple times across the past week
• restarting my computer, as dinnerbone suggested. This worked at one point on Monday, then I had to quit, then restarted it and it hasn't worked since.

If I can get more data on this for you guys, I'd be happy to; I halfway know my way around a command line.