Just posted a comment on someone's blog, and had the normal iPhone related glitches. I pressed the send button and it brought up a little dialogue "Duplicate comment detected: it looks like you've already said that"
Now obviously this is Mumsnet, so it should be "it looks as if" but otherwise I think that's a bloody brilliant idea. Can you do something of the sort? It would save all the smartphone users looking like mad spammers all the time and stop us having to do tedious apologies.