Yes, it's happening more an more lately. The title in the SERPs is being custom built for the individual search itself. It has always been that way in individual cases - where the title is too long, for example. But now, more and more reports are coming in about this kind of customization.
Same happens in yahoo search. For my targetted keywords in yahoo, the listings have been static for past 1 year or more with customised titles for each listing (gives a feel that those rankings are manually adjusted), most of these listings in the serps are listed in yahoo directory as well, so it might be possible that they are pulling the titles from the directory!