Old news: that the USPS has used electric vehicles (EVs) since at least 1899.
Newer news: that Congressman Jose Serrano introduced a bill – called the American Electric Vehicle Manufacturing Act or "e-Drive" (H.R. 4399) last December for the USPS to use a fleet of 20,000 electric delivery vans and to get a network of 24,000 charging stations (with more to come). There is a summary of the bill here (PDF).
Newest news: there are things being done behind the scenes to push EVs into the fleet sooner rather than later.
This week, during the Washington Auto Show, EV advocates are holding meetings with Congressional staffers about this very issue. The e-Drive bill just got a new website, which gives people who aren't in D.C. a way to support the bill and to contact their Representatives and Senators to voice that support.
We haven't heard much about the all-electric USPS minivan that Chrysler displayed last Earth Day recently, but that doesn't mean that the Postal Service is standing still. AC Propulsion and a company called AutoPort will be converting a traditional USPS Grumman LLV, the "long live vehicle" that is the standard mail truck used around the country, to electric drive. The test vehicle will use AC Propulsion's AC-150 drive system and have a range of up to 300 miles at 60 mph.