The ShareThis people sent me a very nice e-mail:
The ShareThis plugin on your website has been updated!
If you would like to customize the look of your widget, go to the ShareThis Options page in your WordPress administration area
…and the new plugin looks great, and has different themes!
And then you discover that all you have to do is merely mouse-over an icon and it greys out your blogpost and opens up a Share-With-Twitter (or whatever) dialogue.
And plonk, it goes straight in the trash.
BAD, BAD SHARETHIS PEOPLE. NAUGHTY!