Amazon.com website actually runs on AWS for last 2-3 years.

It sure didn't when I was there three years ago, but maybe they moved quickly.

Not true...

It runs 100% on AWS.

Not all of amazon runs on AWS though, since they use a service oriented architecture, but many of the services also run on AWS.

Judging from alpb's post, they either currently work there, or did in the past. "retail website" being the key phrase used frequently internally to Amazon.