Depends if the shower ceiling has a soffit or the same height as the rest of the bathroom. Be sure to install a properly sized exhaust fan with auto humidity controlled switch. See Broan-Nutone. Try treating your tile and grout with BioShield-75. Helps keep mildew at bay.

Tiling the ceiling of a shower is still a viable option. A few things to consider: 1) for your comfort the ceiling inside the shower should be vaulted or domed, not flat so that when condensation turns to water droplets you don't have cold water dripping on you rather then running down the walls, 2) Blue Ridge's comment regarding the exhaust fan is very appropriate and I would take it one step further to suggest that you install the fan over the tub/shower (and with an integral light), this will alleviate the need for the tile ceiling, 3) color seal all tile work to minimize maintenance and mildew opportunities and reapply on scheduled intervals, 4) wire lights and fan together to ensure the fan's use by all bathers, 5) squeegee all tile after every shower to send moisture down the drain and reduce maintenance, 6) use liquid or glycerin type soaps to minimize soap scum on tile and grout and lastly NEVER use bleach based cleaners on tile grout, they will compromise the grout asking it porus and susceptible to moisture intrusion and mold growth.
We have had a lot of success with Benjamin Moore's Bath & Spa formula paint.

My bathroom remodel will start next week and I am tiling my ceiling in Tub/shower. we will ad a ventilation fan (currently there is none) but I'm not putting it in the shower ceiling as I don't like the look of that. I do have a light in ceiling over shower and will buy a newer model but keep the light.
Our ventiliation fan will be tied into the shower light so it will come on anytime someone takes a shower, assuming they turn on the shower light. But it's just my husband and I and at our age, we like the extra light in the shower.

Here's an example of tiled ceiling. you'll find others by looking in the bath photo section.