CainIV - 7:08 am on Nov 30, 2011 (gmt 0)
Staying diversified insofar as the anchor text and rigid guidelines for where you choose to work with in terms of potential links covers 99.9% of the risk in my opinion.
Taking it any further is 95/5 and is something I do when I am at the top of the ranking heap and want to stay there.
I believe brand links are developed through signals.
One signal is to use your business / brand name often in your inbound links.
Using a link analysis excel which shows you all percentages for competitors along with exact keyword percentages and brand percentages helps. We tend to use an excel randomizer for anchor text selection except where we are not in any control of the anchor text we receive.