A communiqué from Swimming Canada today outlined the rule amendments, passed recently at the FINA Congress in Doha, UAE, which will go into effect immediately.
The most notable change is in breastroke, where the single underwater dolphin kick off starts and turns will be permitted at any time prior to the swimmer's first breastroke kick - no more trying to define where the start or "initiation" of the pull occurred.
The full text of the statement from Swimming Canada, including all of the new rule changes (including backstroke, officiating, allowance for underwater electronic lap counters for 800/1500, and a few others) is available for download here.
As long as we're talking breastroke, I often get people asking what the deal is with the "hands must be separated" rule in breastroke. I found this on the FINA website recently to better illustrate what is allowed and not.