I just read about Link Building in Seodigit.com, and here is the summary of link building.
Link building recommend to copy and paste of your blog to other blog. But this blog may become the victim of Google sand box because of the obligation and rule on how blog will well-known on the internet. Copy paste will sacrifice of your blog into the unreliable blog, so search engine will not recognize your blog anymore and don’t want to browse over your blog.
So you must be careful of this program, because if your blog become not recognize again by search engine, so you will not have blog that available in search engine, consequently you will loose your earning, because you can’t write article on your available blog and worse again if your blog become block by Google search, its mean that every time you open your blog, you will get message that this address have been eliminate from internet.