ReadWriteWeb: John Curran, President and CEO of the American Registry for Internet Numbers (ARIN) is warning that the available IPv4 Internet addresses will run out in about a year. Because IPv4 limits addresses to a 32-bit number, there are about 4 billion possible addresses. However, all but six percent of those have been allocated.
The solution is to transfer to IPv6, which uses 128-bit addresses. Curran says that transition is happening "slowly."