Hi, All WordPress blogs are subdomains of wordpress.com and they may have same IPs. Do links from multiple (hundred) wordpress.com blogs help in SEO? Thanks.
Generally well maintained Wordpress Blogs are quite strong from the link juice point of view. Wordpress' system allows you to focus on content, and traffic automatically flows in. You can't assign an individual factor to each link, but it will help. And mind you, Wordpress are pretty strict on the SEO spamming strategy. Any minute hint of you selling a link, and your account will be suspended for violating their Terms of Service.
Yes, also wordpress.com shows quality content in their global tag listing example as "art" which help you for good exposure and content promotion through their network.
Get links from wordpress blogs with high PR and focusing as the same niche as you. Definately one of the most popular, well used techniques of link building
If you are going to link exchange with wordpress blog then you should consider strong content, good traffic and the blog should be relevant to your site. That will good to link.