I really enjoy the Google Maps software, but noticed some of the images are well over a year old (we've been meeting in our new church building since 6/06, but GM still shows a small hole in the ground).

Does anyone know how often the satellite images are updated?

It depends where you are and if there is some good reason to rescan your area it will get done.
i.e.: The town of Vail, CO paid Keyhole\Google earth to run a high res scans of the valley of Vail. It only takes $$,$$$$ to have a downward looking sat to move over your head to take a new pix.

Google Earth Help Center - How old is your satellite imagery?

So, I wonder how often Google updates if no money is changing hands?

Every few years or so for major areas (cities, suburbs, etc.) Not sure how often for places in the middle of nowhere, most likely not often.