Yep. Good Old Games has SS2 now available for download for $10.
As one of the few people on this planet that has never played it (Liz and just about everyone else has told me how awesome it is and how Bioshock while a decent spiritual followup and a great game in its own right still pales by comparison), I quickly snatched it up.
It's $10, which might be a bit high for a game that old, but then again, it's one of those games that I've never heard anything bad about. And Irrational Games, the only company involved in its making that is still around today, had apparently all but vowed that they weren't ever going to release it again.
http://www.gog.com/gamecard/system_shock_2