Yeah but did you see on Jurrasic Park that they sued frog DNA to finish the sequence? i doubt that'd work in real life. Not every sequence would be in a drop of blood. Not everything thats needed anyway.
They are currently carrying out work on recreating the geonome of the Woolly Mammoth and are almost half completed, it is easier to do this then with something like T Rex etc, as there are closer living relatives such as the elephant...
No, the DNA structure would have to be nearly completely intact. They wanted to do this on that Mammoth, but the DNA wasn;t good enough. You need almost perfect DNA to clone somethign. I read this in Popular Science last week. Was interesting.