Some of the language wasn't clear to me either regarding gifting levels until i tried it out for myself.. currently sitting at 1 priest and 3 locks (1 day 2 hours playing time at lvl 47 by questing, and some instance runs). So I wanted to test out the gifting to my main account (my goal was to get a 60 of each class on my main account, so i can switch easily at wotlk if i decided i wanted to solo a different class) And here are the results:

To grant a lvl, the target has to be 1 level lower to be eligible... this means that even though im 47, and the target is 46, it will gift the target to 47, so at lvl 59, if you use it then, you can gift them to 59, but not higher.

So if you wanted to gift 4 lvls to a hunter from 55-59, your gifter can be 59, and it will work.

So if the gifter is 38, he can gift someone up to 38. To be eligible for the gift a lvl, you must be 1 level lower.

I dunno if this cleared anything up for anyone, but hopefully it helped in some way