As you may have heard, AMD has officially released Richland, the APU that replaces Trinity. It improves on Trinity's Turbo by taking temperature under account to take advantage of any available headroom, like Intel's Turbo or NVIDIA's boost. More at the Tech Report: http://techreport.com/news/24482/amd-intros-35w-richland-mobile-apus
The reason I'm posting this here is that if AMD is doing this for APUs, I don't see why they wouldn't do the same for GPUs at some point either this year or in 2014. The obvious downside is that the new algorithm isn't deterministic anymore, but I guess AMD figured that an extra 2~10% or so in benchmarks was worth it.
I believe AMD have started introducing a boost feature that does something like this, it is available on the 7900 series chips.