146
Mozilla released a Firefox Nightly test build with vertical tabs - gHacks Tech News
(www.ghacks.net)
A place to discuss the news and latest developments on the open-source browser Firefox
So will this deprecate the Tree Style Tabs plugin?
Depends on your use case. TST doesn't just do vertical tabs, it shows a tree view of child tabs which might be useful if you need that.
Yup, its supposed to also speed things up as well.