We are experimenting with enhanced user card mouseover popups and have enabled them network wide. You can tell which users will trigger the popup because they have a 3-D drop shadowy look to their gravatar:
Hover your mouse over the gravatar and wait. Note that the user card mouseover popup will only be displayed if the following conditions are met:
Is the profile complete, and long enough? We enforce a minimum length requirement.
The user's reputation must be >= 1k
If you have more links than are able to be displayed after truncation, those extra links will be shown in the bottom of the dialog. We order links at the bottom consistently -- if you include a twitter, google plus, linked in, or facebook those links are prioritized.
It will be visible on a question and answer detail page, any page with a list of questions, and the /users list.
It will not be shown when a question or answer is wiki'd.
It will not be shown when excerpt summary is defined as
<!-- summary: -->
we support explicitly specifying your user card excerpt summary using the following syntax:
<!-- summary: This is my profile, there are others like it but this one is mine. -->
The above example will result in:
This is now mostly complete.
The goal is allow people to show off how awesome they are inline, without having to click through to the full user profile page.