blueheron11, I think we are talking about two different things here.
The online service through photoshow.com is supported on PC and Mac (btw, There is Safari for Windows now). When you are on your Mac, you just need to go to photoshow.com and login then you are good to go.
However, there is a desktop software comes with Roxio Online Premium Service that would allow you to do the following.
Burn PhotoShows to DVD for TV playback
Export PhotoShows to video files (MPEG2, WMV)
Author PhotoShows while not connected to the Internet
Create Shows without waiting for upload completion
This desktop software is not supported on Mac.