I am applying for professor jobs at teaching focused universities (even some SLACs). However, I just accepted a short-term postdoc, at the school where I graduated, that will not affect a fall 2012 start date.
If you make a special point of updating search committees with this information now, some of them will think "hmm... he really wants to be at a research university, and probably won't be a good fit for our teaching-focused institution."
However, if you wait 'til the interview stage, you can present this information in the context of enhancing your capabilities as an undergraduate research mentor.
Still, some teaching-focused places like postdoctoral experience. If so, they usually specify that in the ad. If this is your only p'doc experience, and an ad says "post-doctoral experience preferred," updating the search committee is probably in your best interest.
--Cu
