Interlinking sites with Google Webmaster tools?

I'm sure we all know that Google values inbounds links coming from a site that isn't of the same IP, but is that the only way Google tracks site connections? What about webmaster tools and more importantly, google analytics. Since most people keep all their sites on the same analytics account, do you think google uses it to track connections between sites?

the analytics code it's seems to be more like a footprint ... like adsense code .... loads of peoples suspecting this ...

the analytics code it's seems to be more like a footprint ... like adsense code .... loads of peoples suspecting this ...

I have a blog site that ranks really well for a chosen keyword. About 18 months ago, I set up an online store selling products related to that keyword, and posted a backlink on my blog. The traffic to my online store started coming in.

About six months ago, I added both sites too Google Analytics. I still get the same amount of traffic, but now both sites have a PageRank of 0. I'm not sure whether or not there is a connection there though...