Another major theme recurring through the notes I took at OSCON, something echoed by many people there, is "siloing" -- or, rather, how to recognize it and do something about it.
Simply put, the "silo effect" is when you have different groups of people, each organized under a different aegis -- who ostensibly should be working together to some degree but instead choose to do their work separately. Any reconciliation of effort between groups is done after the fact, if at all, and the end result is many solutions that work in parallel and solve the same problems over and over in different ways. or, worse, each one only solves part of a problem).
Our current OSS gadfly, the Linux Hater, sounded off on the silo effect recently (warning: that link is loaded with non-worksafe language!). He pointed out that it's not something that is new or even exclusive to OSS -- but that, in theory, it is something open source should be better at dealing with: "Everyone can see each other's code. Everyone can modify each other's code. If the developers of some project didn't care about your goals, you could always take their code, and do it yourself. Right? There's open mailing lists and bug trackers so that communication is as easy and as smooth as possible, right?"
(Joe Brockmeier ("Zonker") sounded off on the above as well, although more from the point of view of the Linux community now being more willing to accept criticism of its methods and practices generally than the silo effect alone.)
To me the problem has nothing to do with open source or even software, per se. It's the mentality of the developer: they see their solution to a given problem as the way to do it. This is something that open source can help with -- but that requires a mindset that is receptive to the idea that a) there is more than one way to do something and b) there's a good chance other people aren't going to think it's your way.
This, to me, also is a sign that Linux and open source are moving outside of the exclusive sphere of the developers, which is as it should be. Things that weren't really visible to them -- because they had lived with them for so long -- are now being seen through new eyes.