The brilliant minds behind WordPress have released version 2.8.5 last night, dealing mostly with security issues.
The main fixes of WordPress 2.8.5 are:
- Trackback Denial-of-Service attack fix
- Removal of areas within the code where php code in variables was evaluated
- Switched the file upload functionality to be whitelisted for all users including Admins
- Retiring of the two importers of Tag data from old plugins
It is strongly recommended to upgrade as soon as you can, either via your WP admin panel or download WordPress 2.8.5 directly from here.