Well, the problem is that people looking for MAME for the Mac are going to tend to find "MacMAME" first. Whoever runs MacMAME.org should at the very least update with info about MAME OS X and SDLMAME + frontends (much as the Xmame page has), because I really don't think MacMAME's coming back.
Just tried searching for "mac mame" on Google, and MAME OS X doesn't show up at all. Upon closer inspection of the MAME OS X web page, I realize that I never use the word "Mac" on there at all. I'll rectify that when I push out the next version, and hopefully that'll help the Googlebots.