The Lilypad doesn't work with “shields”, as such.
Are you planning on riding a bike inside a car, or the other way round?
Not to rain on your parade, but why reinvent the wheel?
Get a garmin nuvi for $95, enter the address right on the touchscreen, database is built in so no PC involvement needed.
What constitutes your “LED feedback” which the Lilypad would be used for? This is an area that interests me anyway, and it'd be interesting to know what you have in mind for this kind of visual output.
The GPS module gets the lat. longitude from the satellite, the compass on the GPS module will get the orientation in which you're riding the bike in(N,S,E,W).
Now this information will be sent to Google Maps Street View API( just like iPhone's GPS navigation) and whenver a turn of the street comes, the LED blinks showing the direction you've to turn to reach your final destination.
Got it? :-?
Yes. The LED blinks.
How are you getting google maps data on your arduino? don't you need an internet connection for that?
GSM shield as marked above.