I don't know the omap version of the ARM processor very well, but it's a common feature for ARM CPUs that you can run the frequency up and down almost as you like. At least for Samsung and Intel versions. There are for example lots of utilities around for ARM-powered Palm PDAs to fiddle with the frequency. Note that for Palms it's as common to want to _reduce_ the frequency (say, from 400MHz to 150MHz) as it is to increase it, because the higher frequencies usually result in higher battery drain. My understanding is that the omap has a good set of power-saving features (all of the ARM mobile CPUs have, to some extent), and that Nokia is getting better at it with the newer firmware versions. Which is probably why they now up it to 400MHz.