Using Menu Tabs with Views 3 (Drupal 7)
Check this:

How to add a tab to a Views page:
On the View that you want as the default tab: In the Views ‘page settings’, set the Menu Type as ‘Default Menu Tab’ then click the little setting ‘gear’ and set the ‘parent menu item’ to ‘normal menu item’.  Set the path as “/something/tab1″; for example, “/postlist/allposts”
On the View that you want as your second (or 3rd, etc) tab, set the Menu Item Type as ‘Menu tab’.  Set the path as “/something/tab2″ for example, “/postlist/newposts”
The key to making the tabs show on the View page is the path setting!  All of the pages must have the same parent-path – in the examples above this is “/postlist”.  If the parent-paths are not the same, you will never get that damn tab to show up in the View.

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