Don't you people know why it is 2 fields ? One to send to the search engine provider and one to NOT send to the searchengine provider if you know exactly where you are going. That is why Mozilla didn't combine them and that is why Google did.
At the risk of sounding a bit snarky, don't you know what an execute command is?
Type a search string into a 'universal' field and hit enter = perform a search.
Type a URL into a 'universal' field and hit enter = go to that URL.
Use some refined heuristics to determine the intention (ala the AwesomeBar in Firefox) and you've got the best of both worlds.
I don't use Firefox/Chrome daily, so I may be missing something, but I don't see why a dual address/search field needs to communicate with Google to be combined.
A large part of the reason Firefox chose to keep them separate is for privacy. Everything you type into the search bar is sent to Google--even before you hit enter--for autocomplete purposes. The Firefox team felt that many privacy-conscious users trusted that the URL bar doesn't send info until they hit enter.
With autocompletion it will send every part while you type to the search-engine: p, po, por, porn, porns, pornsi, pornsit, pornsite, pornsite., pornsite.c ohhh, the user meant a URL, I'll stop sending it to the searchengine provider.
