I commented in my review of "Daddy Issues" that Damon had really made good in-roads with Jenna if she's hooking him up with her friends, and she even gave him Andie's number later. Both responded that they thought it was more about Jenna wanting to keep Damon away from Elena after the porch kiss, not to mention their lack of personal space when they first entered the Grill. I tried to remain in lala-land that it was all about Damon's charm (and Alaric whispering sweet-nothings about Damon in Jenna's ear). Alas, a rewatch showed that I was pretty much wrong. While obviously Damon has made some in-roads -- she did give a friend his number -- it clearly was mostly about keeping him from Elena. Check out this snippet, and note Jenna in the background looking upwards in frustration as Damon blows off Andie and heads straight for -- you guessed it! -- Elena.
Yup, they were right, I was mostly wrong. Alas, my dreams of a Jenna completely fallen for Damon's charms will have to wait for another day!