I made them in musicmatch itself.
I made a music library in musicmatch of now about 15gig worth of mp3's. This is a custom made library from the 60gig of mp3's that are actually on my Pc's HD.
I then manually choose each file from that library that I wanted to be in a specific playlist. Yes, this was A LOT of work. I had to check 2000+ files four times (and swore a lot). I then saved that playlist.
I repeated this process 4 times, until I had a playlist for each genre of mp3's. I reshuffled some genres two or three times and save those too, because otherwise it would become boring listening to the same order of tracks every single time.

I then tried to upload those playlists, which failed.
Here's how I thought it worked :
The playlists made in MM refer to MM's own library. The library then keeps track of where the files are on the HD.
If this entire library is copied first to the iPod (which it is), I see no reason why this shouldn't work since the playlists are not referring to a certain spot on the HD, but rather to a certain field in the library (database).

At least that's how I thought it worked. MM could have gone about this entirely different, in which case the playlists could only work if the files they refer to also get uploaded when syncing. I sure hope this isn't the case, because that would truely suck.
This approach of not keeping the file structure might have been workable with the first generation of iPod's (the 5gig version), but it sure isn't with the 20gig version. Everything gets clouded and and it's hard to find anything back it this thick mist. I can 't believe the creators of the iPod haven't thought about that. Even the Neo35 did this! (and that's saying a LOT )