I'm surprised. This forum is usually pretty letter of the rules, and the monk's belt--by the letter of the rules--gives an AC bonus that "functions just like the monk’s AC bonus."
So, searching for "AC bonus" under "MONK" in the SRD we find:
"AC Bonus (Ex): When unarmored and unencumbered, the monk adds her Wisdom bonus (if any) to her AC. In addition, a monk gains a +1 bonus to AC at 5th level."
To break it down: a non monk wearing a monk's belt has the AC bonus of a 5th level monk. A 5th level monk's AC bonus is [wis bonus] + 1. Therefore, a non monk wearing a monk's belt gets an AC bonus of [wis bonus] +1.
That's pretty clear to me.
-z
