N800 was released with Maemo 3 (OS2007) and a clockrate of 330 MHz and when N810 was released with Maemo4 (OS2008) the old N800 were able to upgrade to Maemo4 and it increased the clockrate automatically to 400Mhz just like N810 used. I don't see why nokia can't do the same with maemo5 to maemo 6.

http://arstechnica.com/hardware/revi...07/02/n800.ars
http://europe.nokia.com/get-support-...oftware-update