Increase in traffic to/from DSL subs since August?

[Jared B. Reimer]

Greetings.

Another independent ISP operator and I have noticed a pretty significant 
increase in traffic to and from our broadband (DSL) subscribers since 
August.  It's been a fairly steady uptick, at least in my case, resulting 
in a doubling of overall average traffic to/from these folks since then.

Have others seen a similar trend?  Any thoughts as to what the cause may 
be?  Our best guess a virus/worm, possibly being used as a spam relay or 
other proxy at this point...

Many thanks,

-- Jared