To get the Latitude Longitude for any location

Type below for XML response

http://maps.google.com/maps/api/geocode/xml?address=1600+Pennsylvania+Ave,+Washington+D.C.&sensor=false


for JSON
http://maps.google.com/maps/api/geocode/json?address=1600+Amphitheatre+Parkway,+Mountain+View,+CA&sensor=true_or_false


or type
http://geocoder.us/demo.cgi?address=4950+stevenson+blvd+%2Cfremont+ca+94538
to get the lat and log

for details read below article
http://code.google.com/apis/maps/documentation/geocoding/index.html#Geocoding
http://www.4guysfromrolla.com/articles/060210-1.aspx