It happened with Batman: Arkham Asylum
and it looks like it's happening with Borderlands
as well. Our ole GN staffer, Charlie Sinhaseni, told IGN that they are delaying the PC version
of the game until October 26th in the US and October 30th everywhere else so that they could do some more optimizations on the PC. These "optimizations" are taking a little longer than expected, he said, on the PC side of things. The release date for the console versions is still October 20th.
I can wait a bit as the PC version is my purchase of choice. Chuck's been playing a preview build
for a while now and he really, really enjoys it.