http://www.yellowhours.com

Interesting... but a beatdown to collect the info for one domain.

Are there microformats for hours of operation?

...would be neat if I could prompt for an alert to tell me when a store is open. I'll frequently plan to be at a store at open, but get lost in something else.

This would be a nice tool to modify/implement into black friday marketing.

Also, there are many businesses that could use auto messaging within their own calendar -- like haircut, doctor, massage, oilchange etc services. Send a regular reminder to schedule and appointment, then a mobile reminder shortly before (like outlook) with driving directions.