Is the android:divider attribute under the TabWidget working? I tried the Tab Layout tutorial from android just to test (http://developer.android.com/resources/tutorials/vi
Having the same issue myself. I only see the problem in Ice Cream Sandwich (ICS / 4.0.x). In android 1.6 - 2.3.4 there is no issue, dividers show up properly when setting a drawable in code, or in the xml layout.
I've tried just about everything I can think of to fix it but nothing works, including Josh's answer above :( though I have noticed that when setting any drawable as the divider, it will take up the space between tabs as if there was a drawable there, but it's just not visible.
Hopefully that gives someone else a hint as to what could be happening..?