Apple has released its fifth beta for iOS 6.1 to registered developers. Since the fourth beta was set to expire Monday, we were expecting Apple to seed a new release yesterday or Monday. Instead, the company has uncharacteristically seeded the new software on a Saturday. iOS 6.1 beta 4 was seeded on December 17th, 2012.
Everyone has been expecting the final iOS 6.1 GM build to arrive any day now, but Apple is still obviously pushing out betas. When the GM version does come out for devs, then a public release is not far behind.
A beta version of iOS has never gone past 7 beta revisions in years, and each version is usually about a month apart. That would put 6.1 on track for hitting beta 7 sometime around March, which happens to be around the time that Apple usually holds a press event.