By "tags", I assume that you mean Chapter Markers, that let you jump from Chapter to Chapter forward and back through a movie without the necessity
of using the impossibly slow fast forward/back function.
If that's what you mean, then, no, iMovie 10.1.1 does not support Chapters. However, you can add chapters by moving your movie to Garage Band and putting them in there, or by adding them in iDVD before burning. In Garage Band you can add the chapters precisely where you want them, whereas in iDVD the Chapters can only be inserted by time intervals, e.g, one every 3 minutes, one every 2 minutes, etc.
Aside from the above, you can add Markers to your time line for editing purposes by tapping the "m" key on your keyboard. But these are place markers, not chapter markers.