In one of Google's Matt Cutts recent videos, Matt answered the questions of it is okay to use those expandable web techniques to expand and collapse content. It is okay to use those techniques or is it considered hidden text and against Google's Webmaster Guidelines.
Matt Cutts said clearly that if it is done for user interests and not to spam or manipulate Google's search rankings, then it is okay.
Here is the video:
Here is the transcript:
Today's question comes from Cologne, Thomas asks. How does google treat hidden content which becomes visible when clicking a button doesn't look spam yet most of the text is in such a section. For example a simple page to buy something and show details button which reveals a lot of information about.
Okay I wouldn't be overly concerned about this but let's talk through the different consequences. It's pretty common on the web for people who want to be able to say okay click here and then show manufacturer details, show specifications, show reviews. That's that's a pretty normal indium at this point it's not deceptive, nobody's trying to be a manipulative.
It's easy to see that this is text that's intended for users and so as long as you're doing that I really wouldn't be too stressed out.
But certainly if you were using you know a tiny little on that users can see in there's like six pages of text area and there is not intended for users and there is keyword stuffing then that is something that we possibly could consider hidden text.
But in general if you just have something where you have a nice ajax sort of site and things get revealed that you tried to keep things clean. That is not the sort of thing that's going to be on the top of our list to worry about because a lot of different sites really do that. It's pretty common on the web a lot of people expect that on the web.
Take for example Wikipedia on your mobile phone which have different sections of the few quite expanded sections. And there's good usability reasons for doing that. So as long as you're not trying to stop something in the hidden away that's deceptive or trying to you know distort the rankings.
If you just doing it for users I think you'll be in good shape.
So there you have it, you can hide text only if users can get to it and if it is useful and done not with the intent to trick Google.
Forum discussion at Google+.