Well, my GPS also improved (not that much, 10-20%) after flashing new 2007.51 image.
Never had a real problem with it. The idea is that acquiring a lock needs a clear view of the sky, lack of RF interference and metal objects around helps too.
I was fairly amused when I was checking the maps and forgot to disable GPS... took a lock in like a minute and a half. In the middle of the city.

AFAICS maemo-mapper caches GPS almanac. The problem is that w/o having a GPS run for two days at different times you wouldn't get the locations of all sats with enough precision to be able to predict positions at all times.
It'd be great if maemo-mapper could correllate and correct (at least partially) that stale data vs approximate current position, say, selectable on the map.
Could somewhat improve lock times in cases of reflections.