Apple is still hard at work on iOS 8.1.3, issuing a second beta (build 12B466) to retail employees in its testing group yesterday. The firmware was expected to be released to the public this week, but according to a report from MacRumors, engineers are still trying to iron out bugs.
The site notes that it continues to see a steady uptick of visits from devices running iOS 8.1.3, and iDB can confirm we're seeing similar patterns in our own analytics (above). This again suggests that a public release is imminent, but whether it'll be this week or next we don't know.