From the official description: "a subreddit for tables of recent threads from places such as... /r/IAmA, /r/InternetAMA, /r/AMA, /r/AskReddit, /r/AskScience"
It makes things nice to read.
Of course, Bill Gates' new AMA will not be "tabled" yet, but as an example (and in case you missed it), here is his AMA from February 2013 [2].
Like r/tabled, his new iAmA it's not here, but to give the same example, here's his old one: http://www.topiama.com/r/911/im-bill-gates-cochair-of-the-bi...
It's actually a bit surprising to me that reddit themselves have not written an IAMA question-answer view. Celebrity AMAs have become a pretty big draw for reddit, but browsing them from the default view sucks. Perhaps they view it like they do the mobile clients (the community does them better), but it would be nice to have something native to reddit for this behaviour.
As a fellow user of topiama... I am a bit annoyed at how it looks on mobile. What I plan to do is use bootstrap to make a nice responsive layout for all devices. Stay tuned. Probably Spring/Summer.
Here's the source https://github.com/jhawthorn/riama