My view is that the success of business processes–including software–depends on subtle issue of execution, rather than on the concepts that you can explicitly patent. So I think I'm sympathetic to Paul David, et al, who argue against a proposal for the EU that would encourage software patents.
Bessen and Hunt found that the correlation between R&D and patenting in the U.S. over time has been significantly negative. In other words, as software patenting rates have risen, R&D investment in sectors using information technologies has declined. Whether there is an underlying causal relationship remains unestablished, but the U.S. experience warrants scepticism regarding claims that software patenting would contribute to the goal of raising the software R&D investment rate in the European Research Area.
I'm pretty much anti-patent toward anything that can be covered by a lesser form of license or other property protection.