I'm inclined to agree with you but I realize I get a lot of my tech news on Twitter too. I follow many tech and business reporters, and a lot of tech people in general, and doing a search for "pinterest" from people I follow turns up very little. Though I'm not sure if that's inherent to the network – e.g. it's not a general usecase to share pins across Twitter. Still, I see more on my Twitter timeline about Etsy when it comes to people I follow tweeting about something cool they bought or saw.