Sorry this got overlooked. In case you're still wondering, I can mention that the user input can be obtained in various ways, SQLFORM() being one of the easiest. and your controller function would look at request.post_vars. Assuming the Google Maps API uses values passed in the URL, you would just append the values to the base url. Something like
# assume the address 123 xyz street,Hollywood,California comes from a form with 4 inputsaddr_sgtr
addr_str = request.post_vars.housenum + " " + request.post_vars.street + "," + request.post_vars.city + "," + request.post_vars.state
IFRAME(_src='http://www.google.com/maps/api?address=' + addr_str)
(not tested ... I haven't worked with Google APIs, although I saw a demo where GM was used to get the 10 closest Starbucks locations)
/dps