4.22 Southern Gentlemen Prefer Blondes: April 27th.
Georgina Sparks (guest star Michelle Trachtenberg) returns to the Upper East Side after undergoing a major transformation. Chuck and Nate find themselves at a major crossroads in their relationship as it pertains to their mutual interest in Blair. Serena finds her relationship with Gabriel growing more complicated.
4.23 The Wrath of Con: May 4th.
Blair pressures Georgina into making amends for her past bad behavior by helping her in a scheme. The rivalry between Nate and Chuck over Blair comes to a head. Lily hatches a secret plan to help Rufus with Dan's college tuition.
4.24 Valley Girls: May 11th.
Lily remembers getting kicked out of boarding school when she was 17. Nate and Blair's evening at the prom does not go as planned; Lily and Serena clash.
4.25 The Goodbye Gossip Girl: May 18th.
Serena tries to unmask Gossip Girl.
Also, it mentioned that Season 3 of GG is going to be aired on August 31st.
I'm still not sure if these are true, but I thought I should post it here...
-Yams