According to Jezebel.com, L'Oreal is apparently in the process of developing a pill which prevents hair from losing its pigment, essentially preventing gray hairs from appearing.
Before you get too excited, you should know that the pill isn't expected to be available until 2015, and many researchers still aren't sure about the potential side effects, as the fruit extract that behaves like an enzyme to protect pigmentation production remains undisclosed.
The other downside is that the pill wouldn't be able to do anything about gray hairs that you already have, so you'd have to begin taking the product before they've even started showing. The source also explains that consumers would have to take the pill every day for at least 10 years for it to remain effective. As soon as you stop taking it, you would lose pigmentation.
Instead of waiting for this questionable miracle cure, you could always just go for a dye job and protect your color with products like GraftCyte – Post-Surgical Shampoo and GraftCyte – Post-Surgical Conditioner.