What is Web 2.0 anyway? Think of it as a way of thinking rather than a 'thing' or a piece of 'software'. It was named 2.0 because a 2.0 software version is generally a better version than or an improvement on version 1.0. Web 2.0 has to do with software but it is not software. It's a new way of thinking about the internet and who is on the internet. People no longer want to stare at a never changing website. They want to be active and interact with sites. That's where the software comes in – blogging software in general and WordPress in particular.
Blogs ARE Web 2.0! People can interact by leaving comments, signing up for free stuff that you have to give away, and of course, buying your stuff. They are all about simpler design and encouraging interaction with and among others.
It's up to you to create a sense of community. Invite people to leave comments. Put up polls and surveys – people love to offer their opinion. Then blog about the results! You are including your community and becoming one of your community at the same time.
Let's talk about writing in a Web 2.0 world. Write like you talk, not like you write. Be yourself and let people see you and your personality. Be interesting – not stuffy with exactly correct grammar but try to spell correctly and use punctuation that makes sense. Do not make your reader work to read what you write. Use white space effectively – this is not English 101. Write in short but good paragraphs. You can create a new paragraph using the same thought as in the previous paragraph. Make it easy and make it make sense.