Looks like we may see a lot less engine performance differences next year:
FIA explanatory notes for the upcoming meeting with the Teams
When the decision was taken to "freeze" the engines, certain teams asked for and got a period of time in which to address reliability problems and re-tune for 19,000 rpm. Some teams took advantage of this period to improve the power output of their engines. This was not intended. Other teams did not improve their engines, believing performance to have been "frozen". This has produced unfair and inequitable differences in performance. The World Motor Sport Council has therefore decided that engine performance will be equalised in accordance with the 2009 Sporting Regulations in order to re-establish the position as it was when the freeze was agreed.
The FIA would like to discuss with FOTA technicians how best to achieve equalisation in a way which is fair to all and involves minimal cost.
Source: Ed Gorman's
F1 blog