I don't expect to overclock it stable at 1ghz on the N900. (Although would be cool)
But from what I can see, 800mhz is easily possible and very stable with this CPU.
That would make EasyDebian and emulator games etc run MUCH better imo.

I come from the overclocking world of PCs. I know that EVERY CPU is always overclockable. So I'm sure N900's CPU can.
There is always at least 10% to 50% headroom at stock voltage and temperature so that they are stable at the rated clock 100% of the time.

The fact that N900 can run at 600mhz constant for hours on end tells me straight up that it can easily run at 700-800mhz without issues also.