Wow... I wish she could be on the season more often. Her character really makes all of them go crazy. It would be fun to have her hooked up with Howard Wolowitz. Yeah it sounds difficult, but it would be for the fun sake.
Just one episode and kicked almost everyone in the butt. That was a bit rude. Penny is already about being hitted by the bush. At least she understands what they need. Moreover she could probably fix some of them. Specially teach Leonard Hofstadter how t be nice around Penny.
Great show by the way. Works very well when you are in the mid of your exams, that is full mathematics.