A security and maintenance update for WordPress was released last night and addresses a number of bugs and a small set of security patches.
One of the security patches fixes a problem that has been in all previous versions of WordPress so it is particularly important you apply this as soon as possible.
If you are already on the latest WordPress release (number 3.5) then this update is minor and you should apply it immediately.
What bugs does this WordPress release fix?
One of the bugs that you may have seen is that sometimes when you switch between Visual and Text modes the HTML in your page will be messed up.
Other bugs are security related and include vulnerability in using pingbacks, which could potentially be used to expose information and compromise a site. This affects all previous WordPress versions.
Are there any problems with this release?
One thing to watch out for is that there is a known issue if your site is running on Internet Information Server (IIS). Most people will probably find they are not using IIS, it tends to be less popular for the general public. If you are and you see “Destination directory for file streaming does not exist or is not writable”, then there are additional steps for you to follow.
You can read all the details on the formal WordPress release notice at WordPress.org