That's a very tricky point you raise there Bob.
Often the exif data can be used for the wrong purpose. Take for example
what you can read in the image if it's left there. Many EXIF readers
will omit the part about the serial number and if the camera is in
sequential numbering mode, weather or not it's being used by a working
professional.

So let's take a scenario when someone posts a picture with full EXIF
data from a very expensive camera with a doubly expensive lens on it.
Some low life uses a forensic or  advanced EXIF reader and extracts the
camera and the lens's serial number. Even the flash serial number on
some makes.

They put in a stolen camera report and say the found an image from it
posted by such and such. The poster gets put through a heap of crap by
the cops, maybe has their house turned upside down too just because they
shared information with 250 million people and one of them was a nasty
bastard.

Take heed Bob. The Internet is a dangerous place to put information.
Usenet is absolutely not what it seems and the people you think you are
having a conversation with may be priming you as a target for their
criminal activities.

Take care,

- --

from Douglas,
If my PGP key is missing, the
post is a forgery. Ignore it.

Nor will there ever be any EXIF data in any of my photos that are posted on
the internet.  EXIF data is reserved to paying customers.  As for being sure
I use a D3, let me look.  Oh crap, you're right, it's the totally Fabulous
40D I've been shooting with.

Rita