Yup. I haven't seen one that doesn't.
Chess software and chess 960

I have been wondering this too. evertVB and myself have been playing some good games, but so far he is the only person who has wanted to play 960 (my other challenges have been declined)
I am on Linux, and I have been having a very hard time even finding any decent chess software at all on Linux.
GNU chess plays like deep blue against me and kills me in 12 moves with no way to adjust difficulty it seems. I have been using it to "teach myself" by learning the perfect lines it plays against my openings , but once in a while I'd like a casual game that lasts more than 5 minutes.
Any suggestions, please share.
I used to use DreamChess, but it had no options, and I can't even get it to run on the latest version of KDE... I think the project is dead.
Fritz seems to support chess960, but it's not listed here: http://www.computerchess.org.uk/ccrl/404FRC/
Komodo doesn't support it as far as I can tell.
I am on Linux, and I have been having a very hard time even finding any decent chess software at all on Linux.
I think pfren has had some good suggestions.

m-a-k-a-r-i-o-s by the way, did you try open seeks?
I Googled OpenSeeks and didn't find anything... Is this a chess program for Linux?
There are plenty of weak Chess engines available for Linux, and some of those play Chess960 as well. For instance Roce:
http://www.rocechess.ch/rocee.html
You can run it under XBoard, if you have Polyglot installed. (Roce is UCI, so it needs an adapter.) If it is still too strong for you, you can dumb it down by giving it time odds (like a factor 10 or 100).
Check this link:
Game Review w/ Computer Analysis: My Opponent Missed My Blunder
Does chess software usually support chess 960? How about Fritz in particular?
(I mean including the specific castling rules - it's more than just entering a different setup.)