link?
Nate Duncan and Danny Leroux were discussing it in one of their podcasts but I don't know which one exactly(so I don't have a link, I'm sorry). One of the main points they made is that this might be a way for some teams to cheat the system a bit in FA and set up contracts that even though deemed unlikely are actually likely. For example giving a player that was injured for most of the year a bonus if he plays more than 25 games(which he didn't play the previous season). This way they can sign the player to a lower number on the cap at the time than he's actually going to end up getting.
edit: Here's a bit more from the CBA FAQ: http://www.cbafaq.com/salarycap.htm#Q74