I am going on a trip with my girlfriend, and while looking at her Google Maps, I saw that it had marked the hotel we were staying at along with the dates we would be there. Right there next to the hotel marker. Impressive, really.
I don't like that sort of thing because you can't depend on it. Even if you had the perfect workflow for it, what about any hotel booking you have that doesn't send an email for Gmail to parse, or Gmail can't parse it? Just seems like an annoyingly probabilistic system. Aside from the obvious issues of privacy and creepiness, like how did Google Maps get information that was supposedly just between me and the hotel?
But my girlfriend absolutely loved it. She just wished it also showed us our bus route and schedule like it apparently sometimes does for her.