As most of you probably know, Spotify released a new version of its client - 0.4.3 (more info, here) which now includes Facebook and local files support (among other things). But using the Windows Spotify client under Ubuntu using Wine, you won't be able to take advantage of these 2 new features out of the box. Both the Facebook connect and local files won't work.
Here is a work-around for both of these issues.
1. Connect Spotify with Facebook under Ubuntu (using WINE)
This is actually very easy. It doesn't even involve the Spotify client directly. All you have to do is open your Linux browser (Firefox, Chrome or whatever) and:
a) go to: http://www.spotify.com/ and log in.
b) go to: https://www.spotify.com/en/account/social/facebook/. Click the "Allow access" button and that is it!
2. Play local mp3 files with Spotify Windows client under Ubuntu (using WINE)
a) Solution 1:
Run the following command in a terminal:
sudo wget http://blog.mrfjo.org/winemp3.acm.so -O /usr/lib/wine/winemp3.acm.so
sudo wget http://blog.mrfjo.org/winemp3.acm.so -O /usr/lib32/wine/winemp3.acm.so
Then configure Wine to emulate Windows XP: Applications > Wine > Configure Wine, on the Applications tab, under "Windows version" select "Windows XP". I had "Windows Vista" set and for some reason it didn't work (Spotify probably knows it's bad =)).
b) Solution 2:
Here's an alternate solution for playing mp3 files with the new Spotify 4.x:
sudo wget http://webupd8.googlecode.com/files/winemp3.acm -O ~/.wine/drive_c/windows/system32/winemp3.acm
Open Wine Config (Applications > Wine > Configure Wine) and ho to the Libraries tab. Under "New override", enter "winemp3.acm" and click Add.
Important note: you'll have to use this work-around (either solution 1 or 2) every time you upgrade WINE!
3. Open Spotify links in your default Linux browser.
By default, Wine doesn't open links in your default Linux browser (Firefox, Chrome or whatever) and you may want this for sharing songs from Spotify on Facebook and so on. But you can change that easily. See: How To Make WINE Open Links In Your Default Linux Browser
Many thanks to Tobal @ Linuxmusica for the second tip. Credits for the winemp3.acm.so file: blog.mrfjo.org
See also: How To Make WINE Open Links In Your Default Linux Browser