Jediknightii.net is up right now and has been up pretty much continuosly (except for an odd outage or two) since JK.net was launched.
Granted, we want people to visit JediKnight.net and LucasFiles.com for files and news on the Jedi Knight Series now, but the old site remained up because it had so much old content on it.
As of a few days ago I've gotten complaints that people can't get files from jediknightii.net files section like they could before.
I just tried it a minute ago and was unable to download the ackbar skin.
I don't know what has become of the files or if this is just a temporary outage. Since I have nothing to do with the files over there I've asked the site owners and my fellow staffers. Maybe somebody will post and fill you in.
In the meantime about all I can say is try another site. You won't find every single file but a lot of them on the other major download sites for now.