Motor trend says:
But the accelerated development of the GMT900s means two interesting technologies are delayed or cancelled. GM has been working on a three-valve, small-block pushrod engine with variable valve timing. The technology, which offers fuel economy, performance, and emissions benefits, reportedly remains in the program for later introduction.

We all have been wondering what happened to that 3 valve head. Actually I thought that GM Powertrain had the head all developed. They also have introduced the variable valve timing on the 60° V6 poshrod engines in the new Impala. Lets build them GM!

Oops!

The variable valve timing makes it to the new truck line in yesterday's GM announcement.
6.0L iron block (LY6) heavy-duty engine with variable valve timing, rated at 350 horsepower (261 kw)*
There is also a 5.3 and a 6.2 liter engine with variable valve timing.