[TUHS] Be there a "remote diff" utility?

[Dave Horsfall]

Every so often I want to compare files on remote machines, but all I can 
do is to fetch them first (usually into /tmp); I'd like to do something 
like:

    rdiff host1:file1 host2:file2

Breathes there such a beast?  I see that Penguin/OS has already taken 
"rdiff" which doesn't seem to do what I want.

Think of it as an extension to the Unix philosophy of "Everything looks 
like a file"...

-- Dave