Hey all-- We built this at http://www.startupworkaway.com (15 geeks in a beachhouse!). It's our first foray into the mobile market but we're pretty excited by the beta feedback/love we've gotten. Would appreciate your thoughts!
Looks interesting enough for me to purchase it. I think it attacks a common calendar problem that's missing in the default calendar app of actions that you want to take as future events become the present. Most apps just offer alerts, but this lets you interact with the others involved in the event.
(edited to fix link, thx)