The difference is that - for a chunk of people - this functionality isn't crap. It's actually useful.
It's out of the way for people who don't care. It's there for people who do. I've seen folk go "that's so cool" when the amazon stuff came up.
This stuff is much closer to the adds folk get in Google search. It's often relevant to what they're doing at the time.
http://news.ycombinator.com/item?id=4864783
The difference is that - for a chunk of people - this functionality isn't crap. It's actually useful. It's out of the way for people who don't care. It's there for people who do. I've seen folk go "that's so cool" when the amazon stuff came up. This stuff is much closer to the adds folk get in Google search. It's often relevant to what they're doing at the time.