If you look at StackOverflow, you will see that community can be a major competitive advantage, as it would be hard for someone to compete well against it.
But, if you look at Facebook and Myspace, community there is less of an advantage, as people may be on both and can shift from one to the other, depending on their mood, or where more of their friends are.
In tech companies, the main competitive advantage will be the employees, as their ability may be your limiting factor, or the thing that will help you continue to advance against competitors. I remember someone at Disney (I am guess Eisner) stating that his most valuable resources leave every night.
I think flexibility is a major advantage. If a virtual reality social networking site was easy to use, and was able to start attracting people, I doubt that Myspace or Facebook could adapt well, for example. If you have a loose coupling between parts so you can switch pieces in and out quickly, and you have picked languages that will enable you to take advantage of new features, then you may be able to compete regardless of how the markets change.
I think focus is an advantage. for a small company, as, if you try to spread yourself too much then you will find that you are not doing any one thing well, but are alright at several things, but, you are competing against companies that do what you do, but they do it well.
when you get larger then focus is more of a detriment. For example, Google has moved away from focusing on search, and now they are trying to define themselves in some other fashion, but, what they are doing is constantly creating waves when they release new products. For example, if they can get the kinks out of Nexus One, then it may force a change in releasing phones that are so tethered to one carrier, as it appears that Google can reduce the cost of the untethered version and still make a profit, since their cost appears to be about $179/phone.
If you can find a way to be known for something done in a better way, then you can have an advantage, as you are on version 2 while everyone else is on version 1. For example, Toyota and their hybrid engines. They are ahead of their competitors, as they were early out and were able to learn from past mistakes, so while their competitors are still learning those lessons, they are learning new lessons from improved technology. Or, if you were the first to use recycled carpet to make carpet tiles, then, you can make deals with companies that remove carpet, and buy their old carpet, which makes it harder for your competitors to compete, as you are locking up the supply more, reducing what they can use.