The big issue is how to implement such ideas. If we wanted to produce a line of albino mice and then include these cells which don't produce melanin but another set of photoactive (and photoprotective!) compounds, it probably is very doable, presuming we have everything already engineering/mutated. To, let's say, do it for you or me, we'd need to knock out the melanin-producing cells in your/my scalp, implant the mutant cell line that produces the necessary compounds, make sure that they are still viable and persistent (and not going to die out after only a few generations), and that they don't affect, for instance, the production of necessary melanin in the brain (if we were to try something like a viral or chemical knockout).

Selectivity (it does what we want and not affect other processes), survivability (it's robust enough to last the lifetime of the organism), and safety (it's not going to kill us) - the big and problematic three. I'm sure the bio/nanotech gurus have other ways of putting it, naturally. Another possibility might be dealing with our immediate surroundings - maybe we can combine known moisture-wicking fabrics with research being done into temperature/light-responsive materials to produce clothing that is adaptable enough for the sweltering outdoors and nippy air-conditioned indoors during the summers.

Having said all of that, I am totally willing to work on clones of Scarlett Johansson to get this project to work. :)

P.S. - Wikipedia is actually pretty decent on a number of topics. Especially if there's a bunch of citations one can check out for one's self.