I'm seeing the URL bar update about 3-5 seconds after I stop typing, and this is when I'm not hitting return. From my tests, it's looking like the browser (Safari in my case) gets pushed a URL update at the same time results appear, but delays updating the URL displayed until things settle down. If I pick a link before the URL bar updates, I always get the last result I typed when I hit back.

If I do the exact steps Bruno last listed with Safari, I see the same thing, but only when I go back before the search then attempt to go forward. Forward twice always returns me to red roses. Never been able to recreate the issue going backwards, only when a forward is in the mix do I see some oddness.