Blizzard has used the patch version 5.0.1 for the Beta, but it may not use that version for live release. The expectation will be for a pre-expansion world event release, but there is no sign of it yet on the PTR or anything but a passing mention of a Patch 4.4. As of July 13th, 2012, a blue post clarifies the use of 5.0.3 for the systems patch.