Scion said:
That is true at least, looks to be +2 LA for any of the core races.
And if the MM and the BoED are the only two sources for the template, then the BoED is definitely the latter version. I have my answer then. Thank you.
Whether this is overpowered or not probably depends on the campaign. Although, the book definately tries to take into account the difficulty of being extremely good, as a half celestial would be. The template also took several pretty heavy hits from the 3.0 version.
Now that I've gotten my answer, we can talk balance.

I'm considering this for a paladin, so the synergy with the template is high. However, it's not perfect, as several of the Half-Celestial abilites are mirrored by the paladin core class (
detect evil, immunity to disease,
protection from evil, holy smite, off the top of my head).
At +4 LA, the template seemed worthless. Sacrificing 4 levels of paladin would mean a net -2 to attacks (and a huge delay in iterative attack progression), less hit points until very high levels, etc. etc. Just was not worth it.
Now at +2 LA, it definitely looks appealing. Power-wise, it strikes me as close to balanced, though on the powerful side of balanced.
The flight that some people seem to believe worth +2 LA (!!) does not strike me as particularly powerful. My paladin will already have a flying mount, and has to be in melee range to do his job anyway. For a Half-Celestial wizard, of course, this ability may be far more useful.