Attached is current version @ 4/1/12 (v0.5.4.73) - works perfectly with my Subaru Bluetooth, let me know how you go.
Installation Instructions (from fayez @ spotify):
NOTE: you will have to redownload your music (this may be prevented by manually copying the apk)
1. Download the .apk file and get it onto your phone (you don't need the AVRCP zip file at all - it's for reference only)
2. Uninstall your current version of Spotify
3. Install the custom .apk (you may need to turn on the ability to install from unknown sources first... It's in Settings > Security for me... Make sure to turn it off afterward)
4. Launch the app and log back into your Spotify account and enjoy.
You won't receive update reminders from the Play store, but will need to check manually (if you do see one, let me know so I can patch it. )
I've been trying to modify the Spotify app so that the title, album and artist information shows up over bluetooth with AVRCP. I found a really helpful site with a patch/diff file showing the smali changes that need to be made. I've had a crack, but I think the current version of Spotify is different to the one the patch was made for.
the patch is set to make changes to one smali file (ad.smali) (smali/com/spotify/mobile/android/service/ad.smali)
however the important parts of that file are now in x.smali (smali/com/spotify/mobile/android/service/x.smali)
Any guidance/help would be appreciated. It frustrates me how my car stereo doesn't show up any useful information (even though it does with the stock music app)
I've attached the original smali, my attempt as well as the patch file.