arduino and usb midi

Dear Arduino Experts,

I have found several examples on the net (e.g. of how to transmit midi with an arduino. This requres setting the baud rate to 31250 but does this only work with the usb version of the board; in the documents it says the serial board only does 9k and 16k baud? Also, if you are able to transmit this serial data over usb, would it be possible to use the arduino as a usb-midi protocol device running directly into software which takes midi input? I don't know whether this would require a specially written device driver or not, but if this was possible then i'm sure it would greatly increase arduino's user base especially among musicians.

thanks for your help