Interesting article in the NYT today that talks about how the cost of patent litigation is outstripping patent profit.
http://www.nytimes.com/2007/07/15/business/yourmoney/15proto.html/partner/rssnyt?_r=3&oref=slogin&oref=slogin&oref=slogin
Not sure how I feel about patents... But I've never met an entrepreneur who was burned by NOT bothering to patent anything (though I've certainly read about 'em).