Knut Urdalen has passed along the announcement about the 1.0 release of the Yii framework for PHP being released (by Qiang Xue).
The Yii Framework builds upon learnings and findings from over 5 years of development of PRADO. If you already know PRADO you'll get the hold of Yii quite fast. The framework is already documented quite well in The Definitive Guide to Yii (a good place to start for beginners), in addition to complete class reference and an active forum where you can meet other developers.
There is also an extension repository and a few benchmarks to help you compare it to some of the other popular frameworks out there.