Let's try to sum things up for people who want to try and use Google Music's great new service AND the already great Media Monkey.

This will sync any changes in MediaMonkey's music or playlists into Google Music, totally automatically.
1) Find, install and activate a script which exports your playlists in a regular and automatic manner in any folder/root of your music collection, or somewhere else, it just doesn't matter as long as you tell WMP where they are in step 3. I would advice you to put the saved playlists into the same music folder to make things simpler. The script named
Export M3Us/Create Playlists for Child Nodes is what I used to do this (I've tried version 3.5.3 and 3.6 so far).
2) After installing, visit the options menu for your new MediaMonkey script under File>Export Playlists>Options. Options I've set that accomplish our duties are:
*export to single folder
*all sub-level of nodes (cmatte recommends this, but I, wormy found it to export playlists of every single artist in my library, which was just way too many extra playlists, so I recommend turning it off)
*relative paths in m3us (important!)
*skip exports of nodes/folder: ^(CD|Disc) ?\d+|Accessible Tracks|Imported playlists
*use regular expressions for specifying paths/folders (important!)
*exclude unavailable files
*ANSI (important!)
*extended .m3u format (important!)
*automatically export on shutdown, and every 60 mins. (wormy likes to use every 5 mins because it exports really fast and uses barely any CPU)
3) Now open our dear old Windows Media Player and set it to NOT reorganize our music collection with names and so on (it should be defaulted to this but you may want to check anyways under Options>Library). We must add our folders that contain our music and those that contain the playlists to the WMP library to let it load/create a multimedia database. Once it loads your playlists should appear into WMP, and be auto-updated shortly after MM updates them! They should show up in WMP after you add your music and playlist folders to the WMP library. If you only add the playlists but not the music itself to the library, you may find that the playlists appear in WMP but they do not sync into google music... Make sure to add both your music and playlists to WMP (it should take a while).
4) Now install Google Music Manager. After the first time you open Google Music Manager set it to check WMP to load all your music. From then on it will be done automatically in background even without WMP open, because Google Music Manager silently opens wmplayer.exe to let it update your library (from the folder that MM is loading your playlists and music into) and load/compare it with the known Google Music one.
5) From now on the whole syncing work is going to be done transparently without any action on your part!!! And it's super cool to see our phones daily downloading to offline the new/modified songs from our favorite playlists

In short, what we have done is made our music go from MM Database -> A folder of M3U files -> WMP Database -> GMM -> Google Music. From google music it will sync to your phone or wherever!