Yes, there was a holiday period dip, as usual. What is different is the longer term (12 month) view
http://www.senderbase.org/home/detail_spam_volume?displayed=last18months&action=&screen=&order=

June 2010 . . . . . 339 Billion/day average
December 2010 . . 92 Billion/day average
December 2009 . .205 Billion/day average
So comparing December with the 2010 peak, or comparing December year to year, there is a huge decrease in the last quarter on 2010.

The steady decline from September to December is most likely attributable to the exposure of Igor Gusev in the Russian media, Russian police action in seizing his computers, and the immediate shut-down of his GlavMed affiliate program that was funding the spammers and providing the pharmacy fraud and fake watch scams.

Maybe you have set your sites on the smaller target when you talk about ISPs and the proxy as a work-around. If you raise your sites to target the registrars who honor contracts to register unlawful domain names then you will be able to cause some real damage. This comment applies not only to Intellectual Property theft, but to all the phamacy spam frauds and fake replica trash too. Imagine the gain in global Internet bandwidth if registrars terminated contracts for every domain used for unlawful purposes.

The Net-Chinese registrar in Taiwan has accepted a service contract to register over 1,000 software piracy sites. It is just this sort of widespread abuse for which legislation like this is needed.

For the last 5 days alone, see the pirate sites listed at http://rss.uribl.com/nic/NET_CHINESE_CO_LTD_.html

For over 1,000 examples in October/November check http://spamtrackers.eu/wiki/index.php/Net-Chinese

If the US can't ensure compliance at home, how can anyone expect to convince the Taiwanese piracy sponsors?

Move up the spammers' food chain. Take a look at Complainterator which is described in the Spam Wiki at http://spamtrackers.eu/wiki

It's the registrars who have the power to knock hundreds - even thousands - of spam sites off their perches in one shot, and in response to one complaint. You can see its success rate there.