From LentzWiki

Contrary to regular patents, software patents are about implementations of existing mathematical algorithms. While they appear like rocket science to lay people, there's really nothing new about these implementations. Simply put, computer programmers reinvent the wheel numerous times every day, as different needs call for different approaches.

While not currently valid in the European Union, numerous patents have been granted there. In essense, they are not currenly enforcable. In the United States, software patents have existed for some time, and a very large number has been granted. It appears to be an interesting revenue stream for the USPTO (United States Patent and Trademark Office). Note that the US has a special "triple damages" clause in its patent legislation: if you knowingly infringe on a patent and end up in court, you're liable to pay triple the damages. So it's generally better not to know. Ignorance is bliss!

For more information on the battle against software patents in the European Union, see the No Software Patents web site. Florian Mueller has written a book about the fight against the earlier EU software patent directive culminating in a surprise victory in July 2005: No Lobbyists As Such (2006 - you'll need a PDF viewer. The book is published under the creative commons license.) The fight against software patents in the EU is by no means over. Pro-swpat lobbyists have great incentives, the stakes are high. However, it is interesting to note that quite a few modern companies are actually against software patents. They feel it hinders rather than promotes innovation.

Links

• Are Software Patents Evil? - Paul Graham
• Cautiously Optimistic - 2007-05-14 blog entry by Mike Dillon (Sun legal counsel)