I actually co-own and develop that website.

We have indexed SummitPost in almost exactly the same way Google does - same number of characters in the snippet, and the top text on the page links to the SummitPost article in question.

If you examine your server logs, I think you will see a bunch of traffic referred to SummitPost by our site each month. We give SummitPost both PageRank in Google's index, and refer traffic. I would think this would be very helpful to the website.