The finale of season one will be on May 13 2010, which will be the 22nd and last episode. Most likly they'll take a break to film more The Vampire Diaries episodes so they should be done by September, and I say that because season one started in September!
The reason they took the breaks is too film more episodes. It's still season one untill May 13! If you want to confirm this or get the summary of any episodes you may cheak her on WikiPedia!
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I got all my information from there, so I own none of what I said except for my words, the ideas came from here and I beleive them! All except the September starting of season two, that WAS mine!