iOS 7 running behind, Apple pulling Mac OS 10.9 developers to get it delivered?

Some rumblings from Daring Fireball's John Gruber on a Branch thread this evening point to possible delays in iOS 7 and perhaps subsequently OS 10.9.

What I've heard: iOS 7 is running behind, and engineers have been pulled from OS X 10.9 to work on it.

As he points out, Apple had this problem/solution before. In 2007, Apple had to devote some Mac resources towards getting the iPhone out the door. The press statement at the time read:

"iPhone contains the most sophisticated software ever shipped on a mobile device, and finishing it on time has not come without a price we had to borrow some key software engineering and QA resources from our Mac OS X team. As a result, we will not be able to release Leopard at our Worldwide Developers Conference in early June as planned. While Leopard's features will be complete by then, we cannot deliver the quality release that we and our customers expect from us.

However, the Wall Street Journal says:

Apple is also expected to ship the next version of its iOS mobile operating system around midyear, other people familiar with the matter have said.

MG Siegler adds:

Since we're talking whispers, the one thing I've heard multiple times now is about some sort of biometric scanner on the new iPhone. Perhaps not surprising given the AuthenTec buy — but surprised it would be this soon. Still, have heard it could be a big part of not only authentication, but payments of some sort (maybe even through Passbook) down the road. The most intriguing whisper: that Apple could charge a fee for devs to use it.

Gruber points out that Apple engineers carrying iOS have protective screens on them so it is hard to see the OS, something we've heard has been common practice for some time.