Support for simultaneous editing

Short answer – no. Long answer – WordPress retrieves and stores info in the database. To pull and push that data live to multiple locations simultaneously would tax the vast majority of users’ servers beyond their capabilities (especially shared hosting). It does let you know when someone else is editing a page or post, but beyond that I think it’ll be at least 3-5 years (if not more) before this is more than a pipe dream in the WordPress world.