Neat, and works well for the toy example with 4 tabs open. I don't really think it would work as well for the "tab collectors" as they think. They seem to be aware of this too, since none of the screenshots in the post have anywhere near what I would consider a significant amount of tabs open. I use the tree style tab extension on Firefox[0], which I cannot live without. Horizontal tabs become useless after about 15…
There are lots of tree style tab fans in here, I am one of them. Hey, guys! I am curious how you organize other things. Do you think in trees in other places (like using Dynalist or Workflowy for notes)? I think many more concepts are fundamentally hierarchical and should be exposed to the user as such (trees everywhere!). What do you think?
I have one exception, though. Mind-mapping.
I will use mind mapping tools for todos and notes. But for real mind mapping I use full blown graphs.