FWIW, mine reports 188KB free while playing music, so there's not much memory free on the Rio...
total: used: free: shared: buffers: cached:
Mem: 3149824 2961408 188416 733184 4096 1339392

My collection is 47GB now (2359 Songs, 211 Albums), but never shrinks! So, I guess this firmware isn't going to work for me for long...