Scuttlebutt no more, Microsoft is officially confirming that there will be an app to sync Windows Phones with Macs. Presumably, it'll work not too unlike the Kin Mac apps. I really don't know why they didn't announce this on Monday.
Given the phrasing, "Later in 2010 Microsoft will make a public beta available of a tool that allows Windows Phone 7 to sync select content with Mac computers," (emphasis mine) I wouldn't hold your breath for full-blown Zune on the Mac though.