being not available for Mac hurts me too, but it isn't the same as Apple which isn't even offering MP3s to Windows or even to Macs alone.
OK, so I take Tom's advice to show my support of unDRMed music and I head over to the Yahoo! Music Store to purchase the Jessica Simpson tune A Public Affair. There's only one problem...I'm not allowed to purchase it! Since I am using a Mac, I can't download and use the Yahoo! software for the store, so I can't do business with them.
I know that the iTMS is a proprietary DRM store, but I'm not given the chance to try out (much less support) the unDRMed music simply because I choose not to use Windows.
So buzz off Yahoo!...you're no better than Apple in the online music business.