Is there any completely FREE turn by turn navigation software. For the n800?

Yes. Google Maemo Mapper and Roadmap.

has anyone tried to compile navit for the tablet?

It runs very poorly on the tablets, needs some serious optimization.
Looks like it could be good if it didn't gobble up every little bit of system resources

I think Roadmap Editor might be a better option for porting, as it was made with PDAs in mind:
http://www.freemap.co.il/roadmap/

I have a very basic question:

If I purchase a bluetooth GPS receiver, and install the necessary software, do I have the equivalent of a basic stand-alone GPS? (ie, real time turn-by-turn instructions without incurring any data usage charges via a cell phone.)

Thanks.

I cant seem to find where I am supossed to go to download Meamo mapper for os2003. I have not installed in past so not sure if I need extra repositories or something else? I am also not sure where you find the maps

Yes, you have a basic turn-by -turn gps system.

You download the maps from the aether after installing Maemo Mapper.

Go to http://www.gronmayer.com/it/ to find the repository.

Imw still confused, where do I find Maemo mapper?

Maemo Garage, Maemo Mapper project page.

Is there anywhere for someone that doesnt understand all the repository issues to just figure out the basics to get the software and the US maps and turn by turn voice? SOrry to be stepping backwards here, but everything else I have installed was from Maemo and just had a green install button, this seems to invove more if you want to get maps and get voice.