The saga of dmfail.com is all the proof you need that there should be a command prefix for Twitter.

What I mean is Twitter should have some special character that signifies that you would like to ask a special feature of the service. It would have to be something that would be available on mobile phones etc. of course, like a colon or dollar sign.

Example. For a direct message, instead of typing this:

d mymom Please send more underwear to me at camp. Ones without my name on them.

You would type this (note the colon):

:d mymom Please send more underwear to me at camp. Ones without my name on them.

That way, not only could people once again start sentences with D (a nickname for a friend, perhaps?), if you entered the wrong command, like this:

:dm mymom Please send more underwear to me at camp. Ones without my name on them.

… your message would be discarded or an error would be returned, saving you any further embarrassment.

So how about it?