Piwik 1.2 has been released last week with very useful new features! You can now track Custom Variables for your visitors. We also improved performance (up to 30%) for large scale Piwik setups. For better analytics accuracy, Piwik now uses first party cookies only.
The Segmentation feature is also included in the release as "experimental", and lets you query any Piwik report for a subset of your visitors. This is currently only available via the API but expect a lot more in the future.
Piwik 1.2 announcement & download - See the list of new features and changes in the blog post.