Hi mattg3
For what it's worth, I have had precisely the same experience. I use rechargeable batteries. Immediately before the update to 10.6.7 the Mouse battery was 72% and the Keyboard 80%.
Immediately after, Mouse 100% (still is!) and the Keyboard 100%, then 80% and now 100% again.
Like you, I have no idea what this means or how or why.
No help to you therefore other than knowing you are not alone.
My guess is: if others checked this out (and who does for heavens sake), they might well confirm that we are not alone.
Ian