Does SAP use Drupal? Yes!
The team at Mikamai provides a writeup about their work on WikiSAP on their own site. It looks like WikiSAP is one of their first Drupal projects. They've already extended a module and contributed their enhanced version back, which is a great way to get started with community participation.
I've included a screen shot of Google translated page from the WikiSAP site below. The design is nice and clean, and it looks like there is a lot of user generated content and social networking functionality.