All of the people above saying "Get over it" probably copy landing pages constantly and are afraid of their copied flogs getting taken down.
Using the same template/design is one thing, exploiting text and images you spent lots of money testing for their own gain is another, and you can definitely put a stop to it.
We don't copy landing pages, and pursue those who copy ours very aggressively, and so far, every time, the copied page has been taken down.
DMCA everyone and everywhere- host, domain registrar, aff network, etc.
If they're using AdWords, send a DMCA notice and their ads will be disapproved in a day or two:
Digital Millennium Copyright Act
The reason so much landing page theft exists is because affiliates accept it as part of doing business. If you actually go after landing page thieves, you will eliminate your lazier competitors and increase your bottom line. Unless you're using an exact replica of someone else's landing page anyway, there is no reason you should be letting this go.