The relationship between Washington D.C. and Silicon Valley just got a little cozier.

President Obama appointed Twitter CEO Dick Costolo on Thursday to an advisory committee on national security and telecommunications.

Costolo thus joins a growing list of tech-world heavyweights, including the one-time chief executives of Google and AOL, who are working with the White House on economic and technology issues.

Twitter co-founder Jack Dorsey, for example, has worked with the State Department on social networking tools to be used for diplomatic goals.

Meanwhile, Silicon Valley has been hiring political veterans from the current and previous administrations. Facebook announced Thursday that two Republican Party veterans will join its District office.

Joel Kaplan was named head of Facebook’s Washington lobbying and policy operations. He was an aide to President George W. Bush and now works as an executive at a Dallas-based energy firm, Energy Future Holdings. Myriah Jordan, former general counsel to Sen. Richard Burr (R-N.C.), will be a policy manager.

The hirings come at a time when Facebook faces increased privacy scrutiny from lawmakers.

“It¹s imperative that we scale our policy team so that we have the resources in place to demonstrate to policymakers that we are industry leaders in privacy, data security and safety,” Facebook spokesman Andrew Noyes said in a statement.

Facebook already had on its staff White House veterans Marne Levine, who was National Economic Counsel chief of staff under Obama, and Sheryl Sandberg, a former chief of staff to President Bill Clinton’s Treasury secretary, Robert Rubin. Sandberg is the company’s chief operating officer, while Levine is vice president of global public policy. (Washington Post Co. Chairman Donald E. Graham sits on the board of Facebook.)

Obama’s relationships with high-tech executives have been highlighted as he ramps up fundraising for his 2012 reelection bid. Last month, Obama held three fundraising events in Silicon Valley, one at the home of Salesforce.com CEO Marc Benioff.

Last February Costolo, Google Chairman Eric Schmidt, Facebook CEO Mark Zuckerberg and Apple CEO Steve Jobs were among the guests at a dinner for Obama at the home of venture capital investor John Doerr. That event wasn’t a fundraiser, but during that same week, Google executive Marissa Mayer hosted a Democratic fundraiser featuring Obama.

Schmidt has been an economic adviser to the Obama White House since the 2008 election. AOL founder Steve Case heads up the administration’s Startup America initiave for small businesses.

Costolo worked at Google from 2007 to 2009, following Google’s acquisition of FeedBurner, which he co-founded in 2004.