Gary,

If you run this command, it should resolve this:

wget -q http://ubuntu.bluecherrydvr.com/key/bluecherry.asc -O- | sudo apt-key add -

You can verify the key was installed correctly by running apt-key list:

/etc/apt/trusted.gpg 
-------------------- 
pub 1024D/437D05B5 2004-09-12 
uid Ubuntu Archive Automatic Signing Key <ftpmaster@ubuntu.com> 
sub 2048g/79164387 2004-09-12

pub 2048R/FB0385C2 2012-01-27 
uid Bluecherry Maintainers <maintainers@bluecherrydvr.com> 
sub 2048R/9628A1CB 2012-01-27

(Also, I'm moving this to a forum post, as it's a common question)

Thanks!

Curtis Hall 
Founder, Bluecherry 
Bluecherry