Well, I think I found the answer to this on good ol' Wikipedia again
http://en.wikipedia.org/wiki/Lactobacillus#Metabolism seems to read they produce lactic acid from sugars.
I also found this, http://www.themadfermentationist.com...oud-bruin.html where he loses about 4 points from his pre boil gravity (so really, losing much more than 4 points!)
I also looked at my notes, and that was 1.022 at 100F, so that makes the OG about 1.026. I measured today and it is 1.008, but there's still a big krausen and lots of movement, so it is definitely not finished.
I'd really be curious if anyone has kept good enough notes to determine the anticipated gravity loss to lacto. I did not take a reading pre-boil (kicks himself), but it also did not occur to me the lacto would be consuming it, but in hindsight, duh
I have 2 quarts of 1.026 wort I saved for priming. If the gravity doesn't finish much lower, I may boil those down and drop it in the secondary and prime with sugar, just to bump the gravity up a bit, but not until I see how low the gravity gets...