The new development release of Thunar, the Xubuntu's default file manger, adds support for tabs browsing.
Release notes for 1.5.1:Interesting release for a lot of users since this releases introduces the much-requested tabs in Thunar. Furthermore the new side pane has some important bugs fixed, the tool bar had a cleanup and is much more compact now and there is a permanent delete option. There are also various speed optimizations in thumbnail/icon handling and a number of bugs fixed.
Here's how to install it in Xubuntu: link.