His real name was James Oliver Rigney, Jr. and he also wrote under the name of Reagan O’ Neal. He had some rare kind of cancer, according to wikipedia “from complications from primary amyloidosis with cardiomyopathy (cardiac amyloidosis).” His cousin/brother announced his death on his blog (www.dragonmount.com/RobertJordan/) , which is currently down due to excessive hits.

You can read the blog post and more at librarything thread, from where I found about it too.