Yes, Ridley Scott has announced that he will be directing a sequel of Blade Runner. There is also speculation that he may create a link between Blade Runner and his other recent sequel (or prequel in this case), Prometheus. This isn't known though, and the worlds of Alien and Blade Runner seem so far apart that it's hard to see how this would be done.

So far Scott hasn't given much away about the plot - the original movie of course was based on the novel Do Androids Dream of Electric Sheep?, which has no sequel. He has said he wants a woman in the lead role and would like Harrison Ford to appear in the movie, even if only in a small role. He will also be working with the Blade Runner screenwriter, Hampton Francher, so the new movie should have a lot to offer fans of the original as well as appealing to those who never saw it.