Unlike the Singer project, which was said to be a straight-up remake, this film, based off a treatment by Warren Ellis, has a much different take on the material. Here's an excerpt from the site.
Even though both projects are set up at Warner Bros., the site speculated that the Ritchie project has the edge, since Singer's project doesn't even have a writer attached and Ellis' treatment is complete. Singer also has many more high-profile projects to tend to as well, such as X-Men: First Class, a Battlestar Galactica film and Jack the Giant Killer in development.
Excalibur was released April 10th, 1981 and stars Nigel Terry, Helen Mirren, Nicholas Clay, Cherie Lunghi, Paul Geoffrey, Nicol Williamson, Robert Addie, Gabriel Byrne. The film is directed by John Boorman.