It's been a long time coming — the folks at GOG have claimed that System Shock 2 was the most requested game to be brought onto the service, considering how difficult it was to actually find and play the game on modern PCs. But now the game is available for purchase at $9.99US.
This version apparently features updates to the original game alongside new material in System Shock 2's soundtrack.
System Shock 2 is seen by many as the spiritual predecessor of the BioShock series, with many of the themes in the game passed through to both BioShock and the upcoming BioShock Infinite. If you didn't get the chance to play it first time round, this is as good an opportunity as any.