Jennifer Rice, at What's Your Brand Mantra, has an interesting post on specialization:

Trying to be all things to all people is one of the biggest stumbling blocks to attracting and keeping customers. Choosing a target market is tough. It means eliminating entire groups of people from your messages. But without focus, you risk a bland, diluted message that means nothing to anyone.

She has lots more great thoughts, so go to the full post to read them.