While there’s an ever increasing trend by worried webmasters resulting in more and more sites nofollowing all external links, it’s not necessarily necessary, or even beneficial, and probably won’t help your rankings anyway.
So, I’ve now removed the nofollow tags from the external links on my site, including blog comments, as hyperlinks are an integral part of the web. As I have a WordPress blog I used the NoFollow Free WordPress plugin, as it has some handy features and saved me the time I’d otherwise have spent hacking my installation.
Of course, I may have to reconsider this policy if inundated with spam, and will be more selective than even about which comments to allow, but rather than be cynical, I thought that I’d give it a go.
I also recently read a great article on dofollowing blogs and how (and why) to write worthwhile comments.
Cheers SEO 2.0!