The GPLv3 is likely to have stronger requirements for sharing back code used in web applications. While I personally think that this is fair, it will be "interesting" for companies using GPLed components in proprietary web applications.
As a consultant, it is often frustrating when customers do not want to simply use a license like the GPL because they worry about protecting their intellectual property. I believe that in almost all cases, any proprietary code in a system should be associated with custom data handling. I am not a lawyer, but I believe that the GPL (even v3) allows GPL systems to share data with proprietary systems via a relational database (or some other type of persistent storage).
Why bother dealing with the GPL, assuming that you don't buy into the social and philosophical ideas of the FSF.org? Because it will end up saving you money! For example, using a GPLed content management system and donating improvements back to the project will save you money and effort every time there is a new release that already has your improvements incorporated.
What about maintaining a competitive advantage over competitors? Any advantage will probably be in both how well you serve your customers and in your proprietary data and data processing software.