Actually you can, sort of, and it is exactly what modern-day dedicated GPS units attempt to do. Using their internal clock, the last received almanac and ephemeris data and operating under the assumption that they are still near the position the unit was last used (which, for most practical everyday purposes, usually holds true), they extrapolate which satellites are/should be visible to speed up the Time To First Fix considerably. These mechanisms, known under a variety of trade names, are common in today's dedicated consumer GPS equipment -- hence creating the illusion for the masses that GPS is a turnkey system, when essentially it is far from it.

Personally, I think it should be possible to implement this "offline AGPS" behaviour on the N900 easily enough, improving the general perception of its GPS hardware quality (which indeed is quite good). Anybody know if there is any documentation available on how to feed the AGPS-data to the GPS receiver?

Regards,
Chris.