Consider that the U.S. government has mandated that as of 2010, manufacturers will no longer be able to produce equipment that contains R-22. That's only six years away. Manufacturers knew this was coming and are in the middle of undertaking the necessary research and development to switch their equipment over to other refrigerants.
Lennox is one of those forward-looking manufacturers and just recently rolled out its first L Series® rooftops to use R-410A. The company was spurred to introduce its R-410A units a little early, due to the request of a customer. Ikea, the furniture retailer, expressed a desire to install "green" rooftop units on three of its new California stores. Lennox responded to the challenge, concentrating its resources to have the rooftops available for installation in less than six months.