Serendipity 1.1.1 was released to fix a few bugs.  This is the first update to Serendipity 1.1 since it was first released at the end of 2006.  The 1.1.1 update does not include any security fixes so you may not even need to update unless you've experienced one of these bugs:

• Windows IIS server cookie/session authentication problem when not running via HTTPS
• Change execution order of trackbacks to properly send them when a failure occurs
• Display proper plugin permissionship restrictions when the admin user is not part of the group that is restricted
• Fixed a bug that some plugins were not able to properly execute in the entry detail view

In a blog post at the Serendipity site, Garvin also commented on the feature improvements that can be expected for Serendipity 1.2.  Users of the weblog application can expect the following in Serendipity 1.2 once it is released : 

• Improvements on the authentication/plugin API sequence to better support future plugins like OpenID.
• Improvements for the Spartacus API
• PDO::PostgreSQL support
• Spamblock plugin improvements
• Improvement tweaks to the permalink system

If you haven't caught on yet, Serendipity is a blogging application similar to Wordpress.  You can find a good description of the features in Serendipity at the project's "homepage".  Here at CMS Report, we of course have posted a few links and articles in the past covering Serendipity.