We live in Europe and are releasing commercial software in multiple countries. Besides of the licensing issues (GPL/LGPL/...) we have a question about patents.

I know that if you're in the US, before you release software, you have to check if there aren't any patents you're infringing upon. I also know most of these patents or usually irrational and form a heavy burden on developers/software engineers.

Now, as far as I know, EU rules are lots more ratinal, but there has been lobbying to also apply the same rules in EU.

http://www.nosoftwarepatents.com http://www.stopsoftwarepatents.eu

So what's the deal actually ? For example, there's mention of a patent on a shopping cart :

http://v3.espacenet.com/publicationDetails/biblio?CC=EP&NR=807891&KC=&FT=E

Is that true ? Is a "shopping cart" patented ???

..................

http://stackoverflow.com/questions/1396191/what-should-every-developer-know-about-legal-matters :

4.Software patent lawsuits are crap shoots. You should not, of course, knowingly violate a software patent. However, there is a small but real chance some company will sue you for violating their patent. This may happen even if you develop your software independently, you never heard of the patent, and the patent covers a technique that is intuitively obvious and almost completely unrelated to your software. There is not a lot you can do to avoid this, given the current USPTO policies, other than buy insurance. The good news is that patent trolls generally sue large companies with lots of money.