Well, Starcraft runs on Macs, so Blizz probably also made Staredit run on Macs (they don't have to do much more than exchanging storm.dll for its Mac equivalent).
There also is "Unknown Edit", an editor that runs on Macs. It is in the making and has not that many functions yet. Other than that, there are not many Mac Editors. The SCMD2 port to Mac isn't going anywhere either, as far as I know...
funny thing, I dled starfire editor last night, but when I open it, it says: Starcraft was unable to open a required file. If this problem persits, try reinstalling the starcraft CD. The problem occured while loading a file [probaly starfire edit]
very few. You could contact xXIanXx on Blizzforums; he's on a mac and even wrote/is writing an editor for macs. Link:
http://blizzforums.com/showthread.php?t=7564