First thing we want to do is switch Banshee to daily build to get the most up-to-date version. To do this open up terminal and type:
sudo add-apt-repository ppa:banshee-team/banshee-daily
sudo apt-get update
If for some reason Banshee is not installed right now (it is by default with Linux Mint 11), you can install it with: sudo apt-get install banshee
Now connect your phone by USB to your computer and set your phone to USB Mass Storage. Open the root SD card directory with nautilus and create a new empty file (right click -> create document -> empty file) called .is_audio_player and edit it with gedit.
In the empty gedit file put the following information (like above) into the text file:
Adding the file to the folder allows Banshee to see that your Android phone is actually a music player. Editing the contents of it will tell Banshee what file formats that the phone supports. The one format that I've had trouble getting to work are *.avi because they use different codecs and I get an error. Now start Banshee up and you should see your phone listed under "Devices" now.
You can import the music from your phone by right clicking on right clicking on the x GB Filesystem and selecting "Import to Library" and that will copy all of your files into the folders. Otherwise you could manually copy the folders from your SD card to the ~/Music and ~/Video folders as well as the playlists and import them into Banshee. If you're importing a playlist, you need to open the playlist with gedit and convert all of the backslashes (\) to forward slashes (/) with the search -> replace -> replace all feature. Once you've replaced all the slashes, try importing the playlist under File -> Import Playlist (try doing them one at a time if you have problems with them leaving songs out).
That's it. Your device should now be capable of syncing to your Banshee Media Player. It may take a little playing with to get the playlists set up for your device and your music set up in Linux and organized. Your videos may also error out depending on if it is supported by the .is_audio_player.
** Extra Notes**
If your video is unsupported by Banshee, you can try adding the MIME-Type to the .is_audio_player by following the format: video/name or audio/name and you can find the name from looking up the extension on wikipedia. For example: audio/mpeg,audio/x-wav,video/mpeg,video/quicktime
I believe Apple devices (iPhone, iPad, and iPod) should all work out of the box with this program because of a plugin that comes installed by default. I'm not 100% positive though, but under Extensions there is one listed for Apple Devices Support listing the three I previously mentioned. I just am not sure what is required to set that up.