Asking what SEO "implementation" is used (or perhaps, more accurate, what SEO principles are used) for a website is like asking what typewriter was used to write a novel... there is no way to tell?
Looking into what design philosophies Magento uses when it comes to SEO will probably get you further.
This is not a magic wand you can wave and suddenly you have "SEO" (and I doubt such tools exist), but a free page where you could find more information on this would be Google.
You will also have to apply these principles from the get-go when developing a website. You cannot have crap navigation and HTML structure and then pour some SEO sauce over it, it just doesn't work that way.