If it is similar to other preferred stock investments made by Berkshire, it is likely that the warrants are activated with the calling in of the preferred stock.. which will be in the future. Also, the 3G partners have the right to acquire additional common stock to total 3% if they meet certain benchmarks... so that will partially offset that.
I believe that Berkshire's intent is to own Heinz forever... as any partners of 3G wish to reduce their holdings, Berkshire will be a very willing buyer... just as Berkshire continues to buy up other companies such as Iscar and Wesco until they eventually own it all. In the meantime, Berkshire gets the advantage of having 3G do all the management work to improve Heinz, and Berkshire gets a bit over 22 dollars PER SECOND, around the clock, on the preferred... tick, tick, tick... each second...:)
The warrants allow Berkshire to buy 46 million common shares at $0.01 per share, in addition to the 425 million shares they already bought for $4.25 billion, so unless Buffett and Jorge Paulo have some gentlemen's agreement it seems the optimal strategy would be for Berkshire to exercise them before Heinz pays its first dividend on the common shares.