There's a caveat though, the layout with the Option (AKA alt) key pressed differs considerably from Colemak.
From the looks of it, they just moved the Option/alt characters exactly the same as the no-modifier keys. So for example, pressing Option+r on a Mac QWERTY Layout produces the ® character. The same holds true for the current Colemak implementation in Lion. The real Colemak would yield a ` character with Option+r.
Here's a pic of it, note the "Co" icon in the menu bar:
Here's the layout with the Option (alt) key pressed of the current Lion Colemak:
For comparison, here's the original Colemak Option/alt layout:
They might change it before they release Lion, but since the only Option/alt characters I use are üäö (which are in un-intuitive locations in Colemak IMO) I could easily get used to using Option+u, which produces umlauts: ¨ (Option+d in real Colemak). Typing an a, o or u after the umlaut results in a ä, ö or ü - same as I used to do back when I still used US QWERTY. :)