Sorry if that sounds offensive, it is not intended this way (but I seem to attract flamewars whenever I talk about 4e).
I am a bit disappointed about this information because it basically just repeats what the designers said. "Combat is simple, combat is cool". I know that by now.
If anything, it just further increases my fear that 4E will focus only on combat and remove any non combat information about monsters. And judging from the Pit Fiend discussions I am not alone with this fear.
Sadly this blog entry seems to further confirm that in 4E monsters will only be XP containers with combat stats. If you want them to use to something besides combat it requires houseruling (=preparation).
I just hope that Combats in the real game are really exiting, because the 4E Pit Fiend doesn't look exiting at all (one trick pony. Protect yourself against fire and this guy is harmless. And just 3 possible actions? It will get boring very fast as the players will always know what to expect).