Apple - Finder open new Finder tab in the same directory

Press cmd + ctrl + o in Finder without any selection (otherwise you will open-tab to the selection if it's a folder instead).

cmd + ctrl + o will open a new tab in the same folder as the currently opened folder.

No need for any extra things in OS X for this ;-)

There is another way to accomplish opening a new tab in the same location, if you don't absolutely need to have it as standard.

Open a Finder window and make sure that the Path bar is shown either by going to View -> Show Path Bar or by pressing ⌥⌘P. You then get the folder hierarchy in a bar at the bottom of the window. Just hold ⌘ and double click any item in that bar to open that folder in a new tab (or new window if not using tabs).

Another similar approach to the one described by Lizzan but which doesn't need the path bar to be visible is to Cmd-click on the current folder in the title bar of your Finder window. This drops down a list of the hierarchical path to the current folder - so the 2nd entry in the list (after the current folder itself) is the parent of the current folder. If you cmd-click on the parent folder it will open in a new tab. To minimise the clicks required if you cmd-click and hold the cmd-click down then when you release it on the parent folder it will open in a new tab.

This approach is very useful if the folder you want in the new tab is actually a sibling of the current folder in the path hierarchy.