I dont have my 328i yet - still 2 months away, my 328i has the Professional Nav but not the extended Bluetooth/USB.
Based on what ive read I think the following is correct...let me know if ive missed anything...
My understanding are the the following options exist (except radio and CD):
1. USB Memory stick in arm rest USB
2. iPod/Iphone in arm rest with BMW Y cable (USB and 3.5mm Stereo)
3. Copy from USB to internal HDD using USB in glove box.
4. iPod/iPhone in arm rest USB with standard apple cable
5. Bluetooth streaming
To use the above options you need:
1. Any model
2. Any model
3. Only with Professional Nav
4. Only with Extended Bluetooth/USB
Worked for me 
5. Only with Extended Bluetooth/USB
Worked for me
What i havnt been able toget a clear picture on is what different functionality exists for these 5 options.
Can anybody add details about how the 5 different methods vary from a user interface/features perspective.
Im interested in:
Are there differences in the controls
Are there differences in the display (including cover art)
Are playlists available
1. Playlists:Yes (Tricky?), Album art:No
Yes
2. Playlists:Yes, Album art:No
3. Playlists:Yes, Album art:Yes
4. Playlists:Yes, Album art:Yes, 2 phones active (for calls) at the same time
5. Playlists:Yes, Album art:? Probably not im guessing, 2 phones active (for calls) at the same time
Thanks to LAnderson23, Rob72