There are several neat enhancements in Kamailio 3.0.0 (released January 11, 2010) that make your config looking better and some operations optimized.
During the winter I wrote the series Best of New in Kamailio 3.0.0, focused on detailing major features brought by 3.0, this is going to be kind of mini-blogging series (max 15 lines about the topic itself?!?!), looking at tips for your config made possible only by 3.0.x, named: "Did you know?".
Here is the table of content: