One measure of effectiveness is the number of copyright
notices received. But the software that Media Sentry et al
use to find infringers is an instrumented automated client
taken the net at an instant in time. The copyright service
companies will use one tool until it no longer can fill the
contracts with the content owners for discovering violators.

Until the abusing public adopts the latest-greatest versions
of bearshare and limewire, the service companies will
preferentially find only the down-revision infringers.
And these are exactly the ones that the down-revision
packet shapers can find, so they appear more effective
than is warranted.

Now, that might not matter. The objective may be
simply to reduce complaints, and whatever works for
that works. But people spending money on these boxes
should be careful to make sure they’re not fooling
themselves. Media Sentry is not, itself, a good source
for unbiased information about what is happening on
the net. I certainly don’t mean that in a sinister way.
Media Sentry is in business to make money, and that is
OK. Those reports they send you are simply not a
reliable thermometer for what is on your network.