Welcome, stranger!
We will upgrade our official sandbox to Confluence 3.2 soon, but if you want to try out the new features now already, just leave a comment below (this server runs the Beta 2 release already). Use the RTE and type "!" or "[" to activate this cool feature. Or check the Confluence 3.2 Beta Release Notes for more in-depth information on how to use Autocomplete and the new Links dialog
Happy Hacking!
Per