I know this has been requested. I think I have a way to do this fairly simple. I could be wrong though.
Have an option on the website to choose several "Manufacturers" and "Models"
For instance
Manufacturer Model Manufacturer Model
Nokia N95 Blackberry Bold
So now a user hits submit and as long as a jr_manufacturer and jr_model field are utilized the program would grab the two products that match the query, then the product thumbs for the intro pics would display at the top of each set of specs with the specs and their field names displayed below. If a field doesn't exist its either left blank or replaced with an X
It seems easy but its probably not, i'd be willing to donate to this effort!
http://www.phonedog.com/cell-phone-research/phonescompare.aspx is one example of how this could work.