The release includes 27 bug fixes and feature enhancements. The scope of this release was primarily focused on improving the current feature set in terms of usability, reliability and support for logging complex objects. You can find the changelog here.
Eran Galperin has written a great post on profiling MySQL queries with Zend_Db and optimizing them by hand.
He explains how to use Zend_Db_Profiler to analyze all SQL queries on a page and how to improve the performance of the queries by adding indexes.
Here is a quick modification to his example that will send the profiling information to firebug instead of printing it to the page.