We absolutely love any screen time shared between Penny and Sheldon on The Big Bang Theory. The dynamic of these two's friendship is amazing.
However, for some twisted reason, some fans want to see them take it to the next level. Recently, series creator Bill Prady put and end to this theory to Ausiello Files.
Bill said: "I will say this: In our season two opener, Sheldon was kind of shocked when Penny casually acknowledged that the two of them were friends."
Prady goes on to dispel the idea by saying, "I think just for Sheldon and Penny to have what she will acknowledge as a friendship is remarkable progress for him. She may be the only friend he's made in a while, so I think everyone's going to have to call that progress. Hoping for more may be way beyond possibility."
I would stop holding out hope, especially since Prady hinted that there will be a huge advance in Leonard and Penny's relationship in the season's last two episodes.