The stssync protocol, outlined at msdn, is used to enable the synchronization to happen.
If you click Connect to Outlook as outlined below

Outlook will then display the following menu

Clicking advanced will bring up this menu

Various tools exists to enabel two-way synchronization between SharePoint and your desktop, of which Microsoft provide Groove as a part of Office while Colligo Contributor seems a far better solution as outlined in this blog. Also refer to this blog for relevant information about how to access information in SharePoint from OWA.
function ExportHailStorm(type,weburl,guid,webname,listname,viewurl,passport,listrooturl,folderurl,folderid)