Update - 7:00PM PDT: We now understand why Blizzard 'changed their minds' and added the portals back. Only Stormwind and Orgrimmar portals were added back to Dalaran and Shattrath City. You still have to hoof it or befriend a mage for the others.
Blizzard removed the portals from Dalaran and Shattrath City last year to go along with the release of World of Warcraft: Cataclysm. It was much-maligned by players, though the studio was steadfast in their decision.
"Portals are removed as we don't want you to have your hearth in an old city from an expansion you've outgrown just so you can have quick and instant travel anywhere you like," Bashiok wrote in a forum post last November. "Those expansions had content that was far removed from things like auction houses and class trainers, and thus, contained portals."
However, it looks like something -- or someone -- has changed Blizzard's mind on the matter. In today's update to the 4.1 patch notes, Blizzard has noted that the portals have returned to both Dalaran and Shattrath City.