Session channel extension to specify home directory?

[Joseph Galbraith <galb-list%vandyke.com@localhost>]

We just had a user request us to start a shell session
for them in an arbitrary directory.

I was wondering what people would think of the following
extension (for the session channel only):

byte      SSH_MSG_CHANNEL_REQUEST
uint32    recipient channel
string    "home-directory"
boolean   want reply
string    path to use as home directory [UTF-8]

What do you think?

Are there security implications?  Is it a bad idea?

Would people implement this in their servers?

(It definetly does not go in the connection draft at this late
date-- perhaps it's own document or perhaps another document for 
extensions to the session channel.)

Thanks,

Joseph