hmmm... this new sparkfun board seems promising, boasting a 40 mi line of sight range and 3000m indoor range and it should be easy enough to connect to the APM. the data transfer is a little slower than the XBee pro at 115.2kbps but should extend the range to possibly farther than your batteries can take your UAV. this would be great for those using gas/glow for long missions. transmits on the popular 900mhz so bad news for those of you in eroupe. i did however send a message to sparkfun to see if they will make a version in 2.4ghz in the future. now to figure out how to break this guy out to USB so it will connect to the APM....
http://www.sparkfun.com/products/9411 Xtend 900 1W board
http://www.sparkfun.com/products/9596 break out board (no headders)
http://www.sparkfun.com/datasheets/BreakoutBoards/Xtend-Digi-Modem-V11.pdf Xtend 900 pin breakout