Software patents are bad. Software is already copyrightable, which means that if you write a fantastic program, people can't copy it and say it's theirs. But if you allow companies to patent what are sometimes the only way of performing a certain action in a piece of code, this effectively means that you are letting them hold the rights to doing something in software.

It's like patenting putting down a load of cement(concrete?) for a foundation for a house. It has to be done. You could probably do it with wood, or clay, but it wouldn't be as good. If I could obtain a patent for it, I could then charge anyone building a house a fee to license the technology from me.

It's just a landgrab, with small, but mainly large companies trying to patent everything in sight, including ridiculous things, trying to grab as many patents as they can, so they can license/sue everybody that wants to use that. Once the large companies are sitting on all the patents, they can just sit back, and protect their monopoly. You can see a short clip about the dangers of software patents here.