I'm just wondering how the limit is determined, as I still have a bit of cross-referencing that I need to do and I seem to have bumped up against a wall.
In the 2.0 betas, the remembered playlist is stored in a 256Kbyte block of the dynamic data partition. This block has a 512-byte header, and the remaining (262,144-512) bytes are used for playlist information.
In that playlist information, each track takes up 12 bytes, and second and subsequent references to the same track take another 4 bytes each. So if you have, say, 4 references to each track (perhaps in artist, album, genre and year playlists) you'll have room for (262,144-512)/(12+3*4) or 10,901 tracks.
I think we talked about increasing this (because, frankly, 10,901 is starting to sound like not very many) but I don't think we've actually done so yet. It shouldn't be too hard to increase it to (512,000-512)/(8+3*4) or 25,574 tracks.
There is currently a hard limit of 28,656 (total of tracks and playlists) for other reasons.
Peter