updated 02:39 pm EST, Mon December 23, 2013
Third beta now seeding to testing partners
The finished version of iOS 7.1 probably won't be released until March, despite expectations, a source claims. Beta 2 was recently seeded to developers; the source says that beta 3 is now being distributed, but only to a closed network of testing partners. That suggests that the code is still unstable, and won't reach a broad base of developers until the new year, or at least after the Christmas holiday.
Delaying iOS 7.1 until March would be unusual, given Apple's tendency to ship iOS updates around January and the progression of the software so far. The first two betas have only dealt with bugfixes and interface tweaks. Given the version number, though, Apple is likely planning major feature additions such as iOS in the Car.