Our friends at Samplepoolz today have the scoop on a new version of the mobile music studio Syntrax
for Symbian series 60 phones like the Nokia 66xx series and Qd phones.
That adds to a number of existing mobile platforms. It's incredible
what you can do with this thing: Syntrax is a fully-graphical real-time
sequencer with 8 channels of audio, built in synths, sampling, looping,
and effects. (And nice to see another site that uses Mambo!)

How might you use this? Aside from having a full studio in your pocket
for sketching on the go, you could easily sync it up with other
instruments in live performance — tap tempo into your computer.

Compatibility: PocketPC, Symbian Series 60, Symbian UIQ (P800, etc.)
Cost: US$12-20

If you dig this sort of thing, Tom Whitwell of Musicthing had a great roundup of pocket music studios on Engadget a couple of weeks ago.