The new reports show you three things in general:
- The domains linking most to your site
- The pages on your site with the most links
- A sampling of the anchor text external sites are using when they link to your site
You can drill down to specific URLs and pull similar data. Here are some pictures of these reports:
This is now live for you to play with in your Google Webmaster Tools account.
I should note that Bing is expected to launch link reports in Bing Webmaster Center soon.