The following kind of act was popular (say) 40 years ago:
Someone claims to be able to read minds.
He says things like
I sense there is someone here named Bill.
Then someone named Bill says
Yes, thats me!
Then the mindreader talks to Bill and seems to
know things about him.
How did the mindreader do it?
He studies styles of clothes
(Mindreader thinks: The way Bill is dressed he must
be a college professor.) He gets Bill to reveal stuff about
himself and echoes it back.
The mind reader may have people who mingle with the crowd ahead
of time and try to overhear conversations.
This took some real skill to pull off.
Fast forward to the year 2008.
The mindreader could get everyones name ahead of time
since most paid by credit card, and google some of
them to find out more about them.
But, the audience knows he can do this.
The more precise his statements are
(e.g., I sense that Bill co-writes a Blog with someone named Lance)
the more obvious it is that he used GOOGLE and hence the
less impressed I would be.
Lets look at this another way: How could a real mindreader convince
us that he wasn't using Google? Or some other high-tech device?
Recall
Arthur Clark's famous quote
Any sufficiently advanced technology is indistinguable from magic.
What is happening here is the inverse or converse or something of that:
In a sufficiently advanced technlogical society it will be hard
for a magician to impress anyone.
I can make the following counter-argument to any claims of the existence of mind reading: If it were possible, animals capable of it would have an enormous evolutionary advantage over those that do not. Think how it could help a cat on its quest for mice, or how in-species mind reading could help social animals. Therefor, one would presume that mind reading would be prevalent in the animal kingdom, but it is not. Therefor it is unlikely to be possible, or at least so complex that it is not likely to ever naturally occur.