National Electrical Code is pretty clear on this, at least as of the 2014 version. It says that if the fixture is above the tub or shower, and within 8 ft. vertically from the top of the bathtub rim or shower threshold, the fixture must be rated for damp locations. If the fixture may be subject to shower spray, it has to be rated for wet locations.
If it were me, I'd install a fixture rated for wet locations, just to be on the safe side.
National Electrical Code 2014
Chapter 4 Equipment for General Use
Article 410 Luminaires, Lampholders, and Lamps
II. Luminaire Locations
410.10 Luminaires in Specific Locations.
(D) Bathtub and Shower Areas. No parts of cord-connected
luminaires, chain-, cable-, or cord-suspended luminaires,
lighting track, pendants, or ceiling-suspended
(paddle) fans shall be located within a zone measured
900 mm (3 ft) horizontally and 2.5 m (8 ft) vertically from
the top of the bathtub rim or shower stall threshold. This
zone is all encompassing and includes the space directly
over the tub or shower stall. Luminaires located within the
actual outside dimension of the bathtub or shower to a
height of 2.5 m (8 ft) vertically from the top of the bathtub
rim or shower threshold shall be marked for damp locations,
or marked for wet locations where subject to shower
NOTE: This code seems to go back as far as the 2008 version of NEC. So as long as your jurisdiction has adopted at least NEC 2008, you should be fine.
You should have no trouble finding fixtures; and/or trim, that is rated for wet locations. In almost all cases, the fixture or trim will be sealed to prevent water intrusion. A quick search through Home Depot's inventory, turned up this item for example.
6 in. White Recessed Lighting Reflector Shower Trim with Frosted Glass Lens
I'm sure you'll find them in all different styles, colors, and from many different manufacturers.