Fulbright & Jaworski, using a link to their slothful web server that requires you to register to get the damn thing, have released their 2008 Litigation Trends Survey. From the press release -

Patent Defense - One-third of U.S. companies, regardless of industry type, had at least one patent infringement claim filed against them in the past three years. For billion-dollar respondents, the level rose to just under one-half, and for invention-rich tech firms, the ratio was higher still at 52%. Manufacturers also saw a high rate of patent claims at 52%, including 2% reporting more than 50 cases since 2005. A notable 12% of below-$100 million companies have been hit with at least one patent infringement claim during that period.

Patent Offense - Equally worth noting, 21% of U.S. companies initiated at least one patent action in the last three years, including 39% for billion-dollar firms.

Patent Volume - The great majority of companies (83%) expect no near-term change in the volume of patent suits. That leaves 12% of respondents expecting an increase of patent cases and 5% of participants expecting a decline.