Michelle Obama turns 49 years old todayTo celebrate, the First Lady gave her White House staff (or, perhaps more accurately, Obama's staff gave her) a new Twitter account, @FLOTUS, where both parties can tweet about exercise initiatives, the White House Easter egg roll, and of course Bo Obama, the First Dog.

We know what you're thinking! Didn't the First Lady... already have a Twitter account? Yes, but @MichelleObama served as a campaign account — she and her staff weren't, and aren't, allowed to use it for official White House business. Remember tweets like this, during the campaign?

(The link goes to a YouTube video produced by Obama for America.)

The First Lady's new Twitter account (which, so far, has issued a single tweet) highlights one of the curiosities of political campaigning on social media. The incumbent candidates of the 2012 election — President Barack Obama and Vice President Joe Biden — each maintained two separate Twitter accounts: one for campaigning, and another for official government business. Under @JoeBiden, for example, Biden tweeted:

But under @VP, Biden stuck to photo-ops, boosterism, and the like:

Under @BarackObama, the Obama campaign tweeted blatant attacks on his opponent, Mitt Romney:

But he kept his White House account, @WhiteHouse, clean of partisan demagoguery:

The divide is especially stark on Twitter, but now that the campaign is over the Obama administration is leveraging their vast campaign list for support. Yesterday, for example, Joe Biden emailed supporters a link to a White House feature detailing the administration's plans to address gun violence.