A new release of the Serial_LCD library suite is available, with support for the AVR ATmega1280 MCU.
Aug 21, 2012 release 334 __AVR_ATmega1280__ added Deprecation notice
Please note that button.define, button.stringDefine and Label are going to be deprecated in the next major release.
Consider button.dDefine, button.dStringDefine and dLabel instead.
The examples have been updated accordingly.
As always, everything is available here