The point is well taken but as the iphone blog points out, (
http://www.theiphoneblog.com/2009/12/09/nuance-…)
if you use any email service you are already sharing way more information
than this. To quote them…

Of course, Nuance is storing all your transcriptions on their servers, which
while not dissimilar to Google, Microsoft, Yahoo!, or Apple storing all your
email, documents, location, etc. is an important factor for users to keep in
mind so as to make informed decisions about services and the companies
behind them….

The should make it clearer that they do this but let's bear in mind that the
only way to not share this data is to unplug completely.

That's really not appropriate and it's disappointing, even it it was for a good reason (from their perspective). I do understand, however, that they are readying a new version that will offer an opt-out.

If you are at all sensitive about your privacy, I'd suggest waiting until that updated version rolls out.