Phase out of R22 Refrigerant and the Alternative R410A
It is widely understood that R22 Refrigerant is being phased out for the new alternative R410A

The EPA has approved R-410A as a replacement alternative to R22, R410A is a blend of hydrofluorocarbons (HFCs) that does not contribute to depletion of the ozone layer, but, like R-22, it still does contributes to possible global warming. R-410A is sold under various names such as GENETRON AZ-20®, SUVA 410A®, Forane® 410A, and Puron®.
Existing units using R-22 can continue to be operated and serviced with R-22, however the costs for R22 will steadily increase as we get past 2010 due to the limitations on production of new equipment and refrigerant. There is no EPA requirement to change or convert any R-22 units and such changes, often referred to as "retrofits," are allowed.

Care must be taken when considering a retrofit as the oils in the two refrigerants are not compatible and the system should be cleaned prior to charging with the new refrigerant. Another thing to consider is is the indoor coil size and the fact that with any older indoor coil combined with new equipment you cannot obtain the SEER or HSPF Ratings for New Air Conditioners and Heat Pump as the size of the coil is directly attributable to the efficiency ratings.
The transition away from ozone-depleting R-22 to systems that rely on replacement refrigerants like R-410A has required redesign of heat pump and air conditioning systems. New systems incorporate compressors and other components specifically designed for use with specific replacement refrigerants.
A Common Sense Approach To Servicing Your System
Any properly installed home air conditioning or heat pump system should only rarely develop refrigerant leaks, and with proper servicing, a system using R-22 can last a long time. If you suspect you may have a leak have it checked and with the costs of R22 getting higher everyday it pays to have your air conditioning or heat pump system with R22 checked and serviced annually by a qualified technician.