You may want to be careful and NOT use the latest snapshots as they are announced to not work: see: Development of openHAB 3.0.0 and 2.5.x where Kai announces that it will be a few weeks before snapshots are becoming usable.
As announced (see above post) add-on updates will become available soon too. Until then, you likely will need to know where to find and where to dop the jar files of any binding you want to update to the unstable version.