On Mon, Jan 28, 2008 at 09:54:01PM +0100, Michael Albinus wrote:
> "Trent W. Buck" <trentbuck@gmail.com> writes:
>> It seems that shell-command (M-!) no longer uses a shell in TRAMP
>> buffers.
>
> Could you, please, test the appended patch? It shall fix the problem.

Confirmed, M-! sh -c 'echo foo' RET works again in TRAMP buffers.

I also tried M-! sh -c 'echo foo' & RET.  I notice that unlike normal
shell-command, it creates a new *Async Shell Command* buffer each
time, and that this buffer does not popup (in a new window).