AVR-Chat

I am designing up a system where a single master AVR has to talk to a
heap of Slave AVR's.

In my previous efforts the slaves have always been on the same PCB, so I
have been used SPI.

Now the slaves are going to be on different PCB's, which comms cables
running between them.

The run length would be about a meter, maybe two meters.

I recall seeing people say that SPI should 'leave the board'.

I have used rs232 in the past, but it means either:

1) Creating a serial communications ring where Master talks to slave 1,
slave 1 talks to slave 2 and slave 2 talks to the master. If one of the
slaves die, its hard to tell which is at fault.
2) Having a master device that has multiple rs232 uarts.

So my questions are these: Is there a better bus to use than rs232?
Are there any Mega's or other chips I can use to get multiple rs232
uarts?
Can you run 4 or 5 rs232 buses on say a mega8 or mega16 by using bit
banging?

The development time for this is short, so I am not sure I can wait for
the AVR CAN's chip to show up.

Any info or tips would be appreciated!

Kind Regards,
Stuart Whelan

Recursion: See Recursion.