An easy and convenient way to Stream from you Mac to the PS3 is MediaLink. It was developed by Nullriver and it cost 20$ for downloading it. You can of course download it for free and try it out but after 30 minutes is disconnected from the system and you have to reconnect it. The price is not high for the multitude of media you can stream and using it for the last 2 months I have never lost connection with the PS3. The supported formats are: MP3, AAC, WMA, WAV ; MPEG1, MPEG2, MPEG4, H.264, DIVX, XVID, AVI, WMV, ASF, MOV, MKV, FLV; JPEG, PNG, GIF, TIFF, BMP, RAW, PDF, PS, EPS, TGA.

It support your iTunes music, iPhoto, Aperture and what is a plus you can add any folder you want from the Mac. The software is constantly undergoing updates, getting better and better and offering more stability, more format support.

Download here.