Currently Pinterest is growing at an astounding rate; if you compare it to FB and Twitter, you can see that the growth rate has boomed. In FB's first two years of business, it saw 6m users; Twitter saw 3m; Pinterest, two years in, is currently on 10.4m. It's also driving more traffic to blogs than Twitter.
It's been touted as "Tumblr laid out like a mood board"; the difference being that its CTA is more intuitive than Tumblr's. You're only ever one click away from the source on Pinterest, meaning that it's a great place to "pin" things you'd like to revisit later. This may spread to other social platforms; one of the main gripes FB users have had in the past is that it's very unintuitive and difficult to customise. MySpace went too far the other way, of course, and ended up with flashy, annoying, difficult to load profiles which eventually just made it a playground for teenagers testing their web design skills.
More after the jump