The improvements that Jeff referred to are now user-testable in the form of Lightroom 3 beta (it was there in the original beta 1, from last October, as well as the newer beta 2, released this week).
Getting back to ACR, I would expect that these improvements to make their way into ACR at some point (given the history of ACR and LR offering rendering & editing parity) but the actual product versions and dates aren't publicly known yet.