While GrandCentral transitions to Google, they have switched from an "open signup" to "invitation only" model. As a current GrandCentral subscriber, I have a few (a very few) invitations to give away; if you'd like to try this service and you're a regular enrevanche reader, drop me a line.
As predicted, Google has actually acquired GrandCentral:
We're pleased to announce that we have acquired GrandCentral Communications, a company that provides services for managing your voice communications. GrandCentral is an innovative service that lets users integrate all of their existing phone numbers and voice mailboxes into one account, which can be accessed from the web. We think GrandCentral's technology fits well into Google's efforts to provide services that enhance the collaborative exchange of information between our users.Official Google Blog: All Aboard
Related: GrandCentral's FAQ on the Google acquisition