This is the first alpha release for Privatemsg 7.x-1.x. Although this version is not yet production-ready, a lot of manual and automated testing has been done to ensure that it works correctly.
There are, however, a few known bugs and planned tasks that will be implemented and fixed in later alpha or beta versions. A full list of these can be found in the issue queue: http://drupal.org/project/issues/privatemsg?version=7.x
This is a port of 6.x-2.x and contains the same features and changes. There are also a few new features which are specific for Drupal 7, including:
Private messages are entities, which means that they are now objects and not arrays. This also means that they use the entity loading mechanism and are fieldable (any number of fields can be attached to them). This also replaces the attachments module. Note that there is currently no upgrade path.
Advanced token support, displays valid and invalid tokens for the author.
Improved rules integration.
Other improvements which are also part of the 6.x-2.x branch include:
Sending messages to roles and planned support for other recipient types (for example, user relationships and organic groups).
* apc_store is already serializing because Drupal saves an object. Simple data structures do not need to be serialized twice #951838.
* Some small changes to be able to run the Drupal Cache Tests while using APC.