Project is retired. See https://attic.apache.org/projects/tiles.html
Tiles 2.1.2 has been released as GA, so a release plan is necessary for the new versions of Tiles.
Tiles 2.2.x series will be a feature-richer verion, that will concentrate on more template language support. In particular, native FreeMarker and Velocity support, whose sources are currently in the sandbox.
An intermediate common layer, that contains all the common code for every template language, should be extracted, to write less code.
Other expression languages support, such as OGNL and MVEL, may be included.
The Tiles 3.0.x will be incompatible with past releases, except of a compatibility layer that could be added.
The things to do are: