[Update 2005-08-11: Please read this post for a clarification on how the PHP works.]
Via Spatially Adjusted comes news that if you have or have access to a WMS (Web Map Service) server — and if you are a GIS pro you probably do — then the WMS maps on it can now be made accessible as dynamically updated layers inside Google Earth.
Australian Chris Tweedle wrote the PHP and posted it, and even adds an IP filter to control access to the server. (To be clear, this code needs to be installed on the server before Google Earthlings can use the maps.)
What this means is that we may soon see vendors selling subscriptions to WMS data layers aimed specifically at the GIS consumer — people like us.
There also appear to be free WMS servers out there for public use, though I haven’t searched far. For example, here is one: The Atlas of Canada. All we need to do now is to convince them to install Chris’s PHP and provide a network link to Google Earth.