We used 1.8rc1, and the positioning was fine.

With 1.8rc2, the autocomplete menu isn't always aligned correctly to its associated input field.
For example, in a page with 4 input fields, the first one is padded a bit to the right, the second one is padded a bit to the bottom, and the others are aligned correctly. Using Firefox 3.5.

In IE7, the menu is aligned correctly in all fields, but its content is always padded to the right.

If needed I'll attach screen shots.