In stock, however because of supply and demand the price is high until stock returns.
http://www.internettablettalk.com/fo...t=26510&page=3
http://www.google.com/products/catal...tle#ps-sellers
http://www.amazon.com/Nokia-N810-Por...6859318&sr=8-1

Maemo 5 is the next generation operating system for the tablet.
http://www.internettablettalk.com/fo...ad.php?t=27242
http://www.internettablettalk.com/fo...ad.php?t=26910

Depends on how badly you want it and your cash flow. The Maemo 5/Fremantle device (suggested name is N900) will not be out or another couple months as the software to run on it is in alpha stage I believe.

Maps and GPS
http://www.internettablettalk.com/fo...ad.php?t=27087
http://www.internettablettalk.com/fo...&highlight=gps
http://www.internettablettalk.com/fo...&highlight=gps
http://www.internettablettalk.com/fo...highlight=agps

just for starters