The trailquest world, sorry MTBOscore, seems to have gone night nav crazy.
Second Dark and White night nav happened just before christmas at Carsington Water. They're doing another two events - Hope area on 3rd of Feb and White Peak on the 9th of March 2012.
There are also events in the next couple of months in the Lakes and on the Isle of Man.
And for those brave enough to go out during the day - looks like there's a new South Pennines league on the go during the summer.