Just a quick note of how we resolved an issue related to an upgrade to Date.

We recently updated Date in our core distribution to date-7.x-2.9-beta1 and on one site, we had a number of date fields set up as just "Date". After the update, the display of all of these ended up 7 - 8 hours off -- when you edit the node, it shows up with the correct time, and when you display the node, it's off by 8 hours.

DrupalDrupal PlanetUpdatesDate ModuleTime zone