SEO Barry Scwhartz blogged about moving to a new office, saying that Google suggested he close his listing and open a new one. However, in doing that, there's no guarantee that he would retain any reviews that had ben posted.
He shares what a Google rep told him: "If you mark the old listing closed, and create a new one, I can't say your reviews will definitely move to the new listing (I can't make guarantees with Places). You could try just editing the address on the old listing, if you're concerned about the reviews, but you might run in to address issues."
It seems odd that Google would suggest this to somebody over simply editing their address. When asked about this, Google told us, "A business owner also has the option to edit the address on their existing Google Places listing." They pointed to this page about doing just that:
But if you're moving, what about the people who are looking for you in your old location? Schwartz notes that Google is supposed to be launching a "We've Moved" option, but apparently that's MIA so far.