We are here and waiting to respond to any first day patch issues you may encounter today. If you do encounter any bugs after patching, please post them here for our team to investigate.
Also, you may want to check reddit as well: http://www.reddit.com/r/leagueoflegends/comments/2ouiq3/421_patch_bugs_megathread/
Currently we have three known issues to report:
* We've temporarily disabled Kalista and Jarvan IV due to some bugs which we are working to resolve at this time.
* We've disabled the Sewn Chaos Orianna skin due to an in-game bug and are working on fixing the problem.