Mega2560 r3 compatable with UNO?

Does anyone know if the Mega2560 is pin for pin compatible with the UNO? If it isn't, where can I find documentation explaining the differences? I am trying to inteface the freetronics Receiver board to a Mega2560 r3 and can't make it work with the sketch from SourceForge. Thanks

rawkitman: Does anyone know if the Mega2560 is pin for pin compatible with the UNO?

The Arduino Mega 2560 is definitely not pin-for-pin compatible with the Arduino UNO. The Mega has a lot more pins. Some of the auxiliary functions are on different pins, particularly the SPI interface. It is found on pins 10-13 on the UNO and 50-53 on the Mega. The various timer inputs and outputs are also on different pins. This chart might help:

https://spreadsheets.google.com/spreadsheet/pub?key=0AtfNMvfWhA_ccnRId19SNmVWTDE0MEtTOV9HOEdQa0E&gid=0

Thanks for the information. Looks like I need a trip to RS to pickup an UNO.