The fact that White House Press Secretary Robert Gibbs is now tweeting is all well and good, but many in the press have taken less of an interest in that fact than what it means for them.

Under the Presidential Records Act of 1978, a variety of official communications to and from White House staff must be archived forever. As communication devices have developed, so has the discussion about just what's going down in history.

Never fear, tweeters! Under the Act, the historical record of your words is strictly limited to direct communications you may have with White House staff. Robert Gibbs' tweets will live forever in the annals of history, but you can freely tweet and re-tweet to your heart's content.

If you get into direct-messaging, or DM-ing, someone at the White House, that message is as good as history.

(Our resident Twitter expert, Major Garrett, explains that you can't DM someone unless they "follow" you, anyway.)

Here's how Robert Gibbs laid it out in his briefing today:

GIBBS: What I write and what I tweet is archived as a part of this Presidential Records Act of 1978 because it is work product created as part of my job at the White House. People that follow me, people that read that, people that re-tweet that, none of that goes into or is archived as a result of the Presidential Records Act.

The only thing that would be archived other than what I produce is if you respond directly to me and only me. It's analogous to sending an e-mail to the White House, which is already archived. So if anybody believed that mentioning me, mentioning the White House, mentioning the president in any of the normal tweets that they do is, of course, not subject to -- subject to the Presidential Records Act.

QUESTION: What if you send something and someone (inaudible) and comments, like "I agree" or "I disagree"? That doesn't go there?

GIBBS: If it only goes to me...