ISAF have released a "Study Version" of the revised rules which go into action on Jan 1st. This is a very large pdf document in which every changed rule is shown in green, and there's a hotlink to a copy of the original "submission" that was presented to propose the change, which shows the old rule and the reasoning behind the change.
You can read/download the study version of the rules here [right click to download if using IE].
The following link is to the ISAF page explaining the study version in more detail.
http://www.sailing.org/documents/racingrules/rrs2013-2016-study-version.php
From what I can gather from on line comments changes seem to me to be mostly subtle as far as those of us who don't push to the last inch of the rules and use them hyper aggressively is concerned, but I haven't been through them in detail. A requirement not to dump litter in the water deliberately is elevated from recommended sailing instructions to RRS, and there are changes about the windward mark rounding which mostly seem to me to be about loopholes and people trying to be clever.
Comments are enabled for this piece, why don't you use them to tell us what you can see looks important.