Things are moving along nicely with the 2 Google SoC projects I am mentoring. Igor is already fairly far along on his project that will add of DML support into MDB2_Schema. If you grab CVS there is a little demo script. Igar has also fixed several issues in the DTD and added an XML Schema xsd that supports much more detailed validation. The main thing Igor will hopefully get time to improve is the API for the new validation class. This should make it much easier to write new parsers or validate existing array database definition structures.
Alex is also hard at work on his project that will hopefully spawn a new set packages that deal with the OpenDocument format. He has already created a fair bit of code and started a PEPr proposal the other day. Please have a look at his work and provide feedback. Especially for new PEAR developers it can be irritating if they receive no feedback until they move to a call for vote because they think all is well.