Lookup on Google Maps

Have a look at the geokit plugin for Rails. I've used it and it will
parse address like the one you've given.
I've used it for something similar and worked a treat.
http://geokit.rubyforge.org/

(PS google recommends that your store the lat,lng co-ordinates in your
database, rather than slamming their geocoder everytime you make a
request)

Cheers, Cam