Unfortunately, the PS3 won't decode .3g format videos. The PS3 will play videos from your phone in other formats such as MP4, VOB, etc... My WD TV Live Media Server will play the .3g files.
If your PC is Vista or Windows 7, you will see the phone in WMP11 as a media server or in Windows Explorer under Network Devices - Media Servers.
You can also access the phone from any browser on your network by entering the URL:
http://<IP_of_your_phone>:9000. This will give you a web interface to the phone in which you can adjust settings as well as access your media.