The XB engine got some upgrades in '08. Larger crankpin and bearings, higher output oil pump, new oil cooler, higher RPM redline, new DDF13 ECM.
The '09 models got "blacked out". The only difference is in the way they look. I think all the black looks cool.
There's a few new additions to the '10 Uly, nothing major. Look on the Buell website and check out the new Ulysses.