Yep, you read that right. In a Late Night with Jimmy Fallon appearance a couple of days back, President Obama mentioned he no longer used his DISA/DOD-approved Blackberry, but a new Android smartphone instead. According to Ars Technica, that device is very likely a hardened Samsung Galaxy S4.
The S4 is currently the only device supported under DISA's DOD Mobility Classified Capability-Secret (DMCC-S) program. In 2014, a number of Samsung devices were the first to win approval from the National Security Agency under its National Information Assurance Partnership (NIAP) Commercial Solutions for Classified (CSfC) program—largely because of Samsung's KNOX security technology. And the S4, layered with services managed by DISA, is the first commercial phone to get approval to connect to the Secret classified DOD SIPRNet network.
The executive branch's early testers include John Kerry, who I imagine has provided as much feedback as the Defense Information Systems Agency can stand. The phones are exceptionally limited in what they can do, too. Like, the cameras-are-deactivated-limited. The phone can be used for calling via secure VOIP, and access email through a secure web version of Outlook. No texting, no web browsing, no traditional telephony.
Given it's the presidential model, it has even more restrictions than usual - John Kerry might actually get to text. There's also some possibility that Obama's new phone is actually a super-top-secret Android phone developed specifically for presidential usage, though given the rather rigorous requirements of DISA's DOD Mobility Classified Capability-Secret program, it would make sense that they'd actually use the phone they'd bothered to certify in the first place.