10 Things Google Wished You Knew

I disagree with number 6, I've optimised existing websites that have errors within the code. Rectifying the code so it becomes valid has led to considerable jumps in the rankings. Valid code helps.

Im curious to know what this articles sources are and how reliable the sources really are considering some of the points made are genuine rubbish while point three is definitely true

Avoid Cloaking techniques

Due to algorithm update Google now is more into quality content and links.

Here nice information is provided regarding SEO i would like to add some more off page facts that is the back links generated for your site should be form good PR site. There should not be spamming, Link generation should be relevant and genuine.

What do you mean by no duplicate content penalty!!!!!!!!

I think before sharing this sort of blog posts you must read yourself Google Panda and Penguin update what are they about and how they are dealing with spamming and duplicate contents.

The OP was posting in 2011, before Penguin and Panda, but to be honest, I think the statement still stands, as long as you are referring to "non-malicious duplicate content".

From the horses mouth:

We had issues from millions of pages of dup content when Panda was first rolled out, with loads of warning messages in Google Webmaster Tools, but we weren't actually penalised, and once we had carried out corrective action (canonicals and 301's in our case) the messages disappeared.