My wife wears a Google Helpouts hoodie and I got a ton of freebies when they launched. It's not like Google wasn't trying ... but it always felt like a half-hearted, let's see if this sticks, kind of attempt ... especially on the software side of things. It didn't stick.
Aside from merchandise, what did they do to promote it? Not saying they did nothing, but I have a feeling that Google collectively (on average) underestimates the degree of promotion necessary to make a product or service successful. They're somewhat spoilt by their big hits.
