If you cast Beacon of Light on someone then they go immune to heals (getting in a vehicle, or dueling is all i tried but I'm sure there are more ways) all of your heals on your self will be doubled. Kinda useless out side of wintergrasp and duels.
Also, Beacon of Light lasts 1min base. 1min 30sec with the glyph, after 1min 30sec the buff will go away but they will still get heals from Beacon for another 20-30sec.
[ame="http://www.youtube.com/watch?v=thmc3ZULjpo"]YouTube - BACON[/ame]
[ame="http://www.youtube.com/watch?v=of8nFtMZDaE"]YouTube - 2min BACON[/ame]