Last information I have (April 2013) says that Poland localization for NAV 2013 has been re-planned, but I don't have any availability date and localization portal (mbs.microsoft.com/.../GFMLocalizationPortalMC_nav) still doesn't mention anything about it.
For law/tax compliance there's this add-on available: navconsolidation.com/.../polish-local-functionality-microsoft-dynamics-nav