http://www.flyertalk.com/forum/Forum1/HTML/007461.html
One to One
CO <--> GR
YX <--> GR
UA <-- GR (UA won't transfer out)
One to Two
GR --> HH
6.7 to One

HH --> GR
CO has recently severed it's transfer relationship with HH, leading some to speculate GR could be next.