@davids355 and others - why such result is not achieved from homepage, since the logo on every page is linked to homepage? it seems google ignores such links from header and footer as far as internal linking goes . thoughts?
I was thinking about this as well. I believe it is first to do with the likelihood of it being clicked. That is why links nearer to the top of the content are considered more valuable.
I had a good example of this last week when I had a web 2.0 with a link near the bottom of the content, exact match anchor to a page on my money site. I moved the link further up the content on the web 2.0 and a week later the page on the money site moved from page 2, onto page 1. So I believe the more likelyhood of the link being clicked, the more powerful the link is in terms of link juice being sent to the target (Regardless of whether its an internal or external link).
Secondly, I believe that Google will also try to determine the relevance of the link and how much weight it should hold with regard to the target of the link.
Consider this analogy -
You make a presentation to 3 people about engine oil and afterwards those 3 people come and speak to me, about your presentation.
The first person is a delivery driver for Dominos Pizza. He tells me that you a little bit about engine oil.
The second person is a doctor, he tells me that you don't know anything about engine oil and what you said didn't make any sense.
The third person is a mechanic working for Maclaren, he tells me you are the most knowledgable person he has met, with regard to engine oil.
Which one do I believe and which persons opinion holds more weight?
I think Google will be looking at this type of thing when they are analysing links - internal and external - and using it to decide how much weight they should give to that link.
So if you have a link from an image that appears on every page on your website, and points to your homepage, how much value does that hold and is it really an endorsement of anything?
Whereas, if you have a page about engine performance, and in that page you have a link with the anchor text "engine oil" pointing to your homepage, how much weight does that hold? Arguably a lot more.