Show schema size with \dn+

Is there any interest in expanding \dn+ to show schema size, similar  
to table sizes using \dt+ in 8.4? We use separate schemas for each  
user, so this would allow us to quickly look up the sizes of each  
user's data.

I have little experience with C and none with the PostgreSQL code base  
-- where should I look to have a go at this?

-- a.