Yes you are right kiran sharma guest blogging has been considered as one of the most important factors in the SEO process in older days. But now-a-days the SEO's are not considering the blog posting as an important one and also not even doing the blog posting for the promotion of a website.
Well, I would say matt cutts is exactly correctly guest blogging show now be considered as good because what most of the seo guys are doing previously was misusing they are exchanging their links, Say you are an seo contact me for guest posting over my site with your link over to my site and I would say let us exchange link you post my site link over to yours and I am going to post yours! This is getting very common day by day and the quality of the work is decreasing down day by day ! So, I would say this is a good move taken by matt cutts.
PS: I guess this information is old I guess matt has stated this on January
Matt Cutts has given statement that guest blogging wont work nowadays.The major taking point at that time in regardance to the guest post was that many bloggers used to spam the post only for getting backlinks and not for posting unique content.If unique and good quality of posts are made , then guest blogging will be effective.
As all the above,
SE bots are very AI,
if links in blog articles, forum posts, et al, do not provide some relevance to the text in the articles, they are considered spam and downgraded.
Guest blogging can be worse than useless, and have a negative effect related to the subject of the page it is posted to
Keep your signature and links relevant to what you post and where, positive results
stray from the rules, very negative results
multiple irrelevant links in mindstreak's signature, bad, spam, will downgrade the sites
single link in Kelly_Burby's signature, web:dev relevant to the thread, good for the site
To the OP, ++ links in your signature, not a good idea