[PKop]

For Google's "trend" purposes, I'm fairly certain this counts as interest in the service, no? Why would it not?

Since they have separate entries for Twitter and the others, listed as "Social network" vs. just simply "search term" this has to imply some difference in what they include as searches.

So perhaps all permutations of searching for things on Twitter, and others, are lumped into the main search term.

[TheBiv]

Definitely!! I just used my personal anecdote to say that my "interest" is rarely with the service it is with the people using the service.