Archive Manager (or File Roller, the real name) has gotten a huge lift with GNOME 2.24. Though, for some reason, the GNOME 2.24 release notes mentions nothing of it, it should be mentioned here.
File Roller supports four new file types! Guess what they are? They're ALZ, RZIP, CAB, and TAR.7Z! How did it achieve this? By getting the help of p7zip, of course! Finally, no more "sudo aptitude install unalz && cd /home/exsecrabilus/Desktop && unalz file.alz"!!!
But there is another thing that has been reworked, that no one would have noticed if it hadn't been for the Alpha 6 screenshot tour.
First of all, Nautilus has a new part of it that can manage archives by itself. I don't know why this happened, and the developers of File Roller must be pissed at Nautilus for taking its job and now becoming an ultimate bloated application that also, has tabs. But basically, this is how it works: You locate to the archive, right click on it, and press "Open with "Archive Mounter""; Nautilus file browser will pop up, pretending the archive is a folder. From there, you can just copy and paste the contents, like you've extracted it. This is particularly useful when you have a 1000 GB archive and want to extract one image from it.
Secondly, File Roller has now fully become a true archive manager. You can slap on a password, and if you don't feel secure even with that, you can encrypt it right there on that spot. Don't know what the option "Split in volumes of....." is, but I think it's neat. :) After reading a comment, I found out that this is for splitting the archive into separate pieces.
Finally. After you have chosen to extract an archive, you can choose to open the archived folder directly; this saves about two seconds of your precious life. This is lovely.