There is new coffee technology for telling freshness in a carafe or on warmer plate on a NASA website for the "Create the Future Contest". The link is listed below. It appears to be pretty simple with a red light emitting diode to monitor coffee freshness and display it continously. I would like to see this technology become commercially available, as it would be very useful for coffee drinkers in general.
Coffee_Addict
This is the link to the NASA sponsored "Create the Future Contest website".
formatting link
The concept is explained in greater detail at:
formatting link