According to Pauseandplay.com in the "More Upcoming Releases" section of their site - Christine McVie is on tap to release an album in the Spring of 2009. Title and Label are TBA.
Interesting to say the least!!
Thanks to dcl1964 on The Ledge for finding this morsel of information on the supposedly retired Christine McVie.
Christine's last release was an album in 2004 titled "In The Meantime".