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There is...

There is Private Browsing! Go to Tools>Private Browsing.

I like it better than Safari's because it sends you to a new window when you enter private browsing (it even tells you to enjoy!), then when you are done, it brings up all of the tabs that you had opened up previously before entering!
 
You can customize the behavior through about:config for Beta 2. Type in about:config into the location bar and you'll see a list of preferences. You can search for "gesture" and find the commands they're defaulted to.

browser.gesture.swipe.up cmd_newNavigatorTab
browser.gesture.swipe.down cmd_close

Just to be safe, you can make a gesture to undo close tab as well.. such as holding shift when doing the close gesture:
browser.gesture.swipe.down.shift History:UndoCloseTab
(about:config, right-click -> new -> string)


browser.gesture.swipe.up cmd_newNavigatorTab
browser.gesture.swipe.down Browser:NextTab
browser.gesture.pinch.out cmd_close
browser.gesture.pinch.in Browser:Home

Maybe toss in a compliment of swipe down with ctrl to go back..
browser.gesture.swipe.down.ctrl Browser:prevTab

Or similar to creating a new tab.. swipe up and alt? meta (cmd)? ctrl? shift? to undo close tab
browser.gesture.swipe.up.alt History:UndoCloseTab
thank you very much, your post was incredibly useful.
 
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