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As long as it is not overwritten, you could use Data Rescue II to scan your hard drive for any file, even if the trash is emptied.
 
I think I can save you two, and possibly three steps.

If it isn't trash, don't put it in the trash.

(Sorry I just got done reading the 'things I hate about Macs' thread).
 
That's for being rude.

Everyone makes mistakes and this is one.

AppCleaner put it in the trash, I just clicked accept without checking the files over carefully enough.
 
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