ImpressCMS (http://www.impresscms.org), a community management system built on PHP and MySQL, has just released a beta version compatible with PHP5.3. Previous versions required PHP5.2 or later, but still had some issues with 5.3. This release is in advance of the upcoming ImpressCMS 1.3 release, which will be completely refactored and will take advantage of the many native improvements in PHP5.
In just under 3 years, the developer team has gone through 40 release cycles and has surpassed 20,000 commits to their SVN repository. In 2009, ImpressCMS was voted the Most Promising Open Source CMS in the Packt Publishing Awards. Built as an offshoot of XOOPS CMS, ImpressCMS has a lot of legacy code, some of it dating back to PHP Nuke! Hundreds of classes are being rewritten and code standards are being applied throughout the core. In addition, a lot of optimization is being done to make sites built with ImpressCMS faster, better and lighter, allowing them to scale better and be mobile-friendly.