Think about this... Google charges you $900 to attend a conference that they will "teach you" how to build apps that work on their systems which benefit them way more than you.
I know Apple charges a developer fee as well.
Amazing how this hacker/developer world works - pay for access to their app stores, pay for conferences to learn how to make apps for their app stores, etc.
It's not zero-sum. The devs get a lot out of it, too. All the devs that buy tickets to IO think that IO benefits them more than the $900 they're parting with.
There were bunches of gadgets given out @ every IO, some to everyone, some to attendees of specific talks.
Also, said developers are planning to make money with these new skills, in addition to networking, I think most people find it well worth it or they wouldn't attend.
I know Apple charges a developer fee as well.
Amazing how this hacker/developer world works - pay for access to their app stores, pay for conferences to learn how to make apps for their app stores, etc.