It was actually "fun" (my definition of fun may be very distorted!) re-reading this thread again today.
The whole issue with having FRESH data/maps is pretty humorous since most of the professional mapping gps' have maps still years out of date in many locations - just read the various forums for TomTom or Garmin. Yes, some areas get updated more regularly but just as many do not. The updates are modest at most and some introduce new errors. So expecting maps of that new subdivision down the street should not be expected for a few years. I was heading to a new Cabela the other day that opened in Nov 2007, and it still is a farmer's field on Google maps, earth, etc. So, let's see, how current are the various mapping programs?
Next, as for map sizes - my TomTom920 has 4 gigs and that fits maps of the US, Europe (and Guam - oddly enough) along with the programming and other features. So clearly static maps could be provided that fit on the SD cards.
The solutions, Trekbuddy and others, that allow maps to be stored are clearly not the easy solution - first, getting the maps takes a bit of effort and then the map-data is not optimized, that is compressed/shrunk, to get a lot of mapping data on the SD cards - they are generally jpg or similar images. But they do work.
Obviously, in another few years these things will work better. Comparing my Garmin45 with my Garmin Vista (both of those units went at a garage sale about a month ago) with my Garmin 76CS and now again the Tomtom - incredible leaps. And my BB is also a phone (G)