before 3-4 year SEO was depend on some spacial work like directory article Pr etc but now when web2.0 trends come in internet marketing all seo technique has been change so now people use web2.0 beside old trends ?
Web 2.0 doesn't change website optimization techniques. As people are mostly spending time on web2.0 sites such as Youtube, craigslist, Twitter, Flickr, digg etc.. online marketers are targeting across these websites to reach such ample of audience. So it is a change in choosing the best marketing channels by opting web2.0 sites to their marketing methods. However, the traditional seo techniques has to be deployed to a site in order to get listed on search engines.
Web 2.0 is a style and technical advance on websites, it has little to do with SEO. Peopl use "web 2.0" properties such as site hosts (weebly.com for example) to create content with links however.