Doggyspace.com has its day as social sites get more focused
mercurynews.com
mercurynews.com
I'm glad someone is working in this space but the tone of the site (acting like you're your dog) seems a little lame to me. Best of luck to them, either way.
I saw dogster a while ago and went, "dang, great idea. Too bad I didn't think of it first." I'm never optimistic enough about the space in a niche for > 1 players.