ESXi 5.5 Update 3a and its associated patch have been released. If you have been following KB2133118 in regards to the the Snapshot Consolidation causing Virtual Machines to crash a fix is now available.
If you are currently running ESXi 5.5 U3 you can use update manager to install the patch.
If you are looking to install ESXi 5.5 U3 from scratch or update from a previous version you should make sure you update to 5.