WordPress 3.4 RC2 was released today, and final is expected sometime next week. For the past month all Dev4Press Free and Premium plugins, themes are tested with WP 3.4 at different Beta/RC stages to make sure that everything is OK. And right now everything works as expected.
WordPress 3.4 is very similar to previous 3.3, and only some of the API changes can affect plugins. There is one major API change that is not yet supported: old ThickBox powered popups are replaced with new ones. But, for now, to avoid compatibility issues with older WP versions, all Dev4Press plugins using ThickBox, with continue to use it.