Yep. Basically, they're buying exclusivity.

Twitter recently bought Atebits, which produced the Tweetie 2 twitter client for the iPhone. Previously, Tweetie 2 was a $2.99 app. Upon acquisition, Twitter released an updated version, renamed it simply "Twitter", and gave it away for free.

You should see some of the negatives reviews that were left. Much wailing and gnashing of teeth, some of it angry that they paid for something that became free (ignoring the value they received in the meantime), but a lot of it sounding like, "I paid for this app because not everyone had it, now anyone can get it? Lame." (That's almost a direct quote from one of the complaints.)

Exclusivity is a tangible item to some people; it's what makes collectors spend ridiculous amounts to find that last item for their collection, or buy $24k Rolex watches. I might personally think it's ludicrous, but there you go.

Specifically, turn off data roaming. (Wi-Fi is fine.)

A trip to Canada in January netted me a $3k phone bill. $3k to use Rogers. There's a few Canadians snickering at the thought right now. ;)

For others in this situation: a call to customer support saying, basically, "OMG three thousand WTF?!" got me retroactively switched for the month to an international data roaming plan; I ended up paying the difference in cost to upgrade, which was still a few hundred, but after you've seen the $3000 phone bill, a few hundred bucks looks pretty good. I also learned very clearly: turn off data roaming, or make arrangements in advance to switch to an international roaming plan (wouldn't have been practical in this case, but would have been for a planned trip).

however the idea of sensors inside your portable devices detecting what you do with them might raise eyebrows even beyond the tinfoil-hat community

Bought an automobile in the last few years? Then you're probably already living with this.