Building instructions are in the file BUILD.txt at the top level of the svn checkout.
These Maven built directory frameworks are slightly different than the ant built directory frameworks. For example, the Ajax framework has dependencies on json, and the ant built Ajax.framework includes a jabsorb-1.2.2.jar, whereas the Maven built Ajax.framework does not include this jabsorb-1.2.2.jar. This is, of course, because Maven dependencies are detailed in the pom.xml, and will be pulled in via standard Maven mechanisms. The frameworks are not interchangeable--at least without manipulating dependencies. There are also a different number of frameworks.