Solar shingles are available from a variety of companies. However, the market success appears to be quite limited. Not too many people are willing to pay a considerable premium for a slight cosmetic advantage.
I've seen people who were quoted $35k for replacing their roof with a non-solar roof and $50k for a roof with solar shingles. Because the solar shingles were an integral part of the roof the whole roof counted for the 30% federal tax credit, bringing that $50k down to $35k.
If they had went with the non-solar roof with a separate solar system installed on top of it the tax credit would only cover that system because the roof is not part of the system.