For the past month, I've been seeing sporadic reports that Google is ignoring the webmaster's title tag and rewriting it to a Google made up title tag.
This new change seems to be a limited test since around June and for the most part, webmasters are not happy about it.
We know Google may opt to change your meta description and use something different in the search result snippet area but page titles?
Anyway, this does not seem to be fully rolled out. I assume if it does, Google will only change your title tag based on the search query used and when they think it makes most sense. Are you comfortable giving Google the keys to your titles in the search results?