in Snow Leopard and earlier, Safari had a spot on the tool bar for a url and also a separate slot for entering a Google search. I don't seem to be able to do this with Mountain Lion. Is there a way to do this?

It is all now done in that one bar. Address bar searching. Just type something, anything, in the address bar and if it's not a URL it will open a Google search page. That is IF you have Google as you search provider.

In Mountain Lion Apple intentionally combined the URL and Google Search bars into a single all purpose bar. It actually makes quite a bit of sense when you consider that you can enter just about anything into the space and Mountain Lion will sort out what to do with it. Apple does not offer an alternative arrangement at this time.

Get Firefox and you won't have that silly combination "omnibar crap," at least not yet--and I'm hoping never. It's a better browser all around. Updated more frequently and much more flexible because of numerous available extensions.