The announcement says that there is "a minimum host allocation duration of 24 hours." So using (and paying) for this instance for just a few hours isn't an option at this time. Knowing AWS, they will evolve this in future iterations.

Huh? I though hotmail was based on Solaris (or SunOS?) servers. And doesn't Yahoo use Linux as well as *BSD?

He mentioned that some Linux security holes were found and people were hammering his box, but there are plenty of *BSD holes too. Just because Linux exploits didn't work on a *BSD box, doesn't mean that BSD is any more (or less) secure. Most NT/Solaris/Irix/AIX/HP-UX/etc. exploits won't work on *BSD boxes either :)