Serial bouncing

I'm working on a project that needs to send multipule serial data streams (GPS, Arduino Mega, weather board, and others) across one xbee. my original idea was to have a USB hub atached to the xbee usb explorer and plug USB to serial cables into that. that would probaly work but is very space consuming.

does anyone know if I could use the mega's multi-serial abilitys to bounnce multiple ports over one port (xbee)

You could send the data in one string and parse the information at the other end. Have you looked into that?