Welcome to the forums, CanadianGuy.
We don't normally do SEO analysis for any site - so please, no one ask for us to look at your project. However, since this is a major retailer and you've noticed something about it, we will make an exception in this case only.
A quick check shows me that they have NOT gained a lot of backlinks this past year - so we can probably rule out that factor. While they didn't increase total backlinks very much, they did gain some new backlinks from domains that never linked to them before, around October 2010. That could be a factor.
What they apparently did do last year is add rich meta-data in the RDFa format to all their product pages, at least according to this Tweet: [twitter.com...]
Now I know that's not a very authoritative source, so my apology on that score. But unless I'd been closely studying them for the past two years, I wouldn't have the data I need to say anything more authoritative.