Most of the changes are under the hood in the way of security fixes, plus there shouldn’t be a need with Mark Jaquith’s plugin for those that were having server 500 problems with WordPress 2.05.

Mark Jaquith has also provided WordPress 2.06 patch files for those that don’t want to do a complete installation. These are unofficial.

Here is a note he also posted on the wp-hackers mailing list

Whatever you do, don’t discourage
people from upgrading. 2.0.5 has multiple XSS issues and a potential
SQL injection issue.

As Mark points out, you should always make a full backup of files and database before upgrading.

I will be upgrading all of my sites over the weekend, and hopefully this will be the last upgrade before WordPress 2.1 is launched, which I suspect will be in approx 1 month.

Feedburner Patch: – If you use feedburner with 2.06, you will also need to add a small patch as detailed at Neosmart