I did compare "dmesg" on old and new SheevaPlug:
old: [42949373.220000] Kirkwood: MV88F6281-A0, TCLK=200000000.
new: [42949373.220000] Kirkwood: MV88F6281-Rev-Unsupported, TCLK=166666667.
Looks like they changed some system chips without further notice!
