The time when hackers where trying to directly attack companies may be over. Nowadays, sensitive information about a company can be found using Google and associated tools. A recent article on SearchSecurity.com explains how hacker techniques may benefit from Google search engine. The author, Bill Brenner, explains the tools used these days by hackers to find useful information about a given company (your competitors could even pay hackers to find such information). He gives many examples of possible tools (e.g. Google Patent Search, Google Blog Search, etc.).
Brenner also warns against the use of blogs inside a company. Intellectual property may be shared involuntarily. I think one of the first (and more simple) example of such information you can find on the web, was regarding the ability of search engine such as Google to mine .doc or .pdf files. Before Google, people could put their sensitive documents on the web and they where somehow hidden since nobody knew the exact URL. Now techniques are more complex as you will see if you read Brenner’s article.