System Shock 2 is NOT Abandonware.
Even if SS2 were abandonware, "ABANDONWARE" IS ILLEGAL TO DISTRIBUTE.
Bottom line, end of story.
Copyrights are not considered abandoned even if they are no longer enforced, so the software does not enter the public domain just because they are no longer commercially exploited or widely available.
For the record, Jeff Brown (Executive President, Corporate Communications at EA) says:
"We pride ourselves in aggressively protecting our intellectual property rights, and we frequently pursue those who try to distribute our games without permission."
There are no titles in the Electronic Arts library that they consider to be abandonware.
Official word from Irrational: "No, System Shock 2 is not abandonware, please don't warez it"
Consider this the final word from TTLG on the subject of System Shock 2's status. Unless we hear otherwise directly from EA and Irrational, all instances involving the sharing of SS2 will be considered piracy.
But isn't abandonware legal?
Simple answer, NO. Despite the fact that publishers no longer derive revenues from these games since they have stopped selling them (and any revenues from retailers that still sell them were gained a long time ago, at the time of sales), it is illegal to distribute them so long as copyright holders have not released them into the public domain, and 95 years after the games' release have not elapsed.
Taken and modified (slightly) from the underdogs FAQ
System Shock 2 can now be purchased from several online stores:
The GOG.com and Steam versions are already patched to at least version 2.4.