Savannah cats are a new breed developed from the pairing of a SERVAL and a limited number of domestic breeds, the siamese being one.
Savannah Cats were developed in the 90's and accepted as a new breed by the International Cat Ass. in 2001. They are banned in Australia unfortunately. (http://news.theage.com.au/national/savannah-cats-banned-from-australia-20080803-3p2n.html)
There are lots more videos of this pair on you-tube. Lovely to watch.