I am wondering if the patent process poses any potential threat to new startup companies and if so what kind. This is referring exclusively to software based startups.

It doesn't seem like patents are talked about much with software based tech startups (in comparison to other industries), especially with everything so open source... but after reading the Dropbox YC application (http://news.ycombinator.com/item?id=801503) I saw the question "Do you have any ideas you consider patentable," which is absent from the current application. I was wondering both why that question is no longer present (or no longer applicable) and whether it is something worth considering about your startup.

I also found the article about Microsoft patenting the process of an OS shutdown (http://www.conceivablytech.com/2530/products/microsoft-patents-operating-system-shutdown/) to be interesting and it sort of raised the question as to whether it is worth searching the USPTO when doing your market research about your web/mobile app so that you don't develop something and then realize that you have to deal with the IP factor.

So does anyone have some experience or insight into

1) The amount of concern a completely software based startup should have with patents

2) When/under what circumstances should patents be filed

3) Whether anyone has any first hand experience either with patent issuing processes or being on the other side of infringing on the patent of another company

I am not saying that anything I have is potentially patentable at all I am mostly just curious about the entire notion of patents and the role they play in startups.