iPhone as Samba Server? My aim here is to make my iPhone 4S (running iOS 5.0) serve its music library over SMB/Samba (Windows File Sharing protocol) so any computer on the LAN can access it.

Are there any iPhone apps available (for a non-jailbroken phone) that can act as a Samba file server for the iPhone's filesystem (or at least music library)?
Out of the box it's definitively not possible. To share music you need an Airplay capable counterpart (speakers etc.).
Also you can share music with iTunes.