This is a border collie. (And an Australian shepherd.)
Isoglossia has linked to my blog with the phrase "border collie." For the benefit of readers migrating from there to here, I am posting a photo of a border collie. Otherwise they might think a border collie looks like a beanstalk, the subject of my last post.
(The border collie is the one on the left. This picture was taken today, by Lilit, who, unlike me, has a digital camera. One of these days I will join the rest of you in the 21st century.)
Update: Many more photos of frolicking dogs here.