Google is in acquisition discussions with telephone management startup GrandCentral, we’ve learned, and we have a high degree of confidence that the deal has actually been closed. We are trying to nail down the acquisition price. Just last week I flagged this company as the most exciting startup we’re currently tracking.

The basic idea around GrandCentral is “one phone number for all your phones, for life.” As we change jobs, homes and cell phones, there are a lot of phone numbers to keep track of, and keeping everyone up to date with your most recent phone numbers is a real cost. If you use GrandCentral you can give out a single phone number. What happens when that person calls that number depends on his/her relationship to you, and what you are doing at the time.

The company, which has raised less than $6 million in capital from Minor Ventures (the exact amount has never been disclosed), beta launched just last September. Earlier this year mainstream press and blogger attention heated up.

The company may have received too much press attention before the product was ready, and we reported on some backlash from beta users abandoning the service in March. Still, the company pushed ahead, launching a mobile product and other features.

GrandCentral was recently pitching a second round of financing to Silicon Valley venture capitalists, but broke off discussions abruptly as the Google talks heated up.

I’m speculating on where Google will use GrandCentral, but the synergies with Gmail and GTalk are fairly obvious and could be the next step in Google’s competition with Skype and other instant messaging platforms.

This is, in my opinion, a great move by Google. Grand Central is an awesome productivity and simplifies the lives of users with multiple phones by giving them a single phone number and letting them handle calls via rules. It’s a natural fit with GTalk and Gmail.

Google won’t comment on this story. I have an email in to GrandCentral to see if they’ll confirm.