I’m still in a very pleased state of shock over the dress Bernadette was wearing.
Here’s the way you work this into the plot:
Wil Wheaton does a favor for Leonard and gets Penny an audition with a new SF series. Penny is mad at Leonard for using his influence to get her an audition, but goes anyway.
She’s a big hit, and gets a co-starring or supporting role on a show with Wil Wheaton. Hijinks ensue. Wheaton joins the cast as a semi-regular. Leonard starts to dislike him because he’s jealous and worried that Wheaton is trying to steal Penny. He and Sheldon join together to plot against Wheaton, who crushes them mercilessly. Penny gets mad at Leonard for being an insane jealous dweeb, but is really kind of flattered that he cared so much.
Wheaton walks away, like Sabu, having hung around while a bunch of crazy people solved their own problems.
There. Now Penny is on a sci-fi show, the writers have an excuse to write Wil Wheaton into the plot whenever they want to, and they’ve got a whole lot of new territory to milk.
Then in the season finale, Penny’s show is cancelled, but she has an offer for a movie… but it’s filming in Vancouver for 3-4 months and she has to leave in a few days. And for some reason Leonard can’t go or visit her there. YEAH, THAT’S THE TICKET!
Semi-hijack:
Has anyone else noticed how very red Jim Parson’s hands are? What’s up with that?
The wife (an RN) thinks it’s because he might have Reynaud’s phenomenon.
I think this is the exact plot for the series! Do you write for the show? 
In a fit of insomnia a few days ago, I re-watched the episode where Lucy was first introduced. It was this years Valentines episode.
IMO, She was not nearly as shy and pathetic in that episode.
It’s not specifically about the final episode of the season, but here is an essay from tomorrow’s Sunday New York Times Magazine praising the series. In particular, he praises Jim Parsons, the ensemble cast as a whole and the writing.