Does anyone know what brands/models of GPS car navigation that is
supported by linux ? ( updating maps and so on )

It should have:
Wifi ( optional, downloads traffic and travel information, this gives
the driver the option to take alternative routes to avoid traffic
IQ Routes ( or something similar ) 1
Map Share( or something similar )2
European maps

IQ Routes

The use of historical route data to improve the route calculation within
a portable navigation device

IQ Routes, developed by TomTom, uses anonymous data accumulated by users
of TomTom satnav devices. This is fed back into the new devices that use
algorithms that take this data into account when calculating the best
way to go. [5]

Travel time data are stored in Historical Speed Profiles, one for each
road segment, covering large motorways, main roads and also small local
roads. Historic Speed Profiles are part of the digital map and updated
with every new map release. They give a unique insight into real world
traffic patterns. This is a fact-based routing system based on measured
travel times, whereas most other methods rely on speed limits or
Ďassumedí speeds.

TomTom started offering IQ Routes in spring 2008 with the TomTom GO 730
& 930.

Map Share is a proprietary map technology launched by TomTom in June
2007. Map Share allows users to make changes to the maps on their
navigation devices and share them with others.

It allows drivers to make changes to their maps directly on their
navigation devices. Drivers can block or unblock streets, change the
direction of traffic, edit street names and add, edit or remove points
of interest (POIs).

Improvements can be shared with other users. Users who connect their
devices to their computers can download and upload map corrections on a
daily basis. This is done through TomTom HOME, TomTomís content
management software.

Users can select various 'levels of trust', only receiving improvements
that have been verified by TomTom or changes that have been submitted by
trusted sources, by many , or by some people.