Patch? Unless it is some severe security issue, XF has not issued patches.  Minor updates (like XF 1.5.5 to 1.5.6) were, I think, every two months, primarily for bug fixes.  Given that this is a new major release, maybe one will happen sooner.  But I don't see that as a valid reason for not upgrading now.
We have to hold off on upgrading since we are awaiting a couple of major add-ons to be converted to XF2 compatibility before we move on.  Otherwise I would have upgraded already.