there are UPnP apps out there for us mac users. I found one that not only made iTunes and iPhoto libraries available to the PS3, but also transcoded flacs on the fly. Too bad it requires an intel mac, as my plan was to re-purpose an old G5 into a media server type thing.
There is another one that worked real well (no flac transcoding though). Can;t remember the names of either off the top of my head but I will check if I remember (and info is still needed) when I get home.
-j