To prevent speculations, let me just say that enhanced proactive detection (I intentionally don't use the word "heuristics" here, as it usually has a more specific meaning) is something we're definitely looking at, and moving forward, plan to spend considerable time on.
It just needs some time (as other things): currently, I somehow prefer to give up bringing big new features in interim builds (currently released approx. bi-monthly) and favor the "accumulate all big new features for the next major release" model...
Yes, I'm talking about avast 5.
I apologize if this post sounds cryptic.