Maps like this are only one piece of the future of parking technology, which might also include online reservations, in-car navigation systems that direct you to an open spot and variable pricing depending on demand.
For now, the biggest problem with Santa Monica's effort may be that out-of-towners, the people most likely to need directions to parking, aren't likely to know that this Web site exists. If every city has a parking availability Web site in the future, that won't be a concern any longer.