I'm a contented resident of the 7th District in Maryland, which means my congressman is Rep. Elijah E. Cummings.

You know who else knows that?

Barack Obama.

I just received an email from Obama, alerting me that there is "a candidate for change in Maryland."

"Dear David," the email says. "You can change politics in this country at every level -- up and down the ballot. Our records show that you live in Maryland's 7th district. There's a candidate in Maryland who'se working to bring the change this country needs, and that candidate is Elijah Cummings."

The email then gives me a link to Cummings's Web site.

I find this to be a pretty slick use of Obama's impressive data-collection efforts, which have been chronicled extensively, including in this piece by David Talbot of MIT's Technology Review.

It's not surprising that Obama would look to help Cummings -- who endorsed the Illinois senator early and is a co-chairman of the Maryland effort for Obama.

But in the old model of politics, it would be the incumbent congressman who turns over his or her resources for a presidential campaign to use. Obama has flipped that model on its head.

Before the angry emails start, let me say this: The Obama campaign has my email address not because I am a supporter or donor or even a registered Democrat -- which I am not. (I am registered as an independent, not affiliated with a political party.) But I did provide the campaign with my e-mail address for journalistic purposes such as keeping track of its solicitations, and accessing information about local events. I did the same with the McCain campaign.

I don't recall giving the Obama campaign my home address, however. (Perhaps I did when registering on their Web site, but it was months ago, and I just don't remember). If I did not, then they used database tools to match my name and other identifying information with my home address and congressional district.

That's even more slick.