Two new gear vendors were added in Patch 5.3 that sell ilevel 232 gear so that you can immediately do the Blackrock Cavern and Throne of Tides dungeons upon reaching level 80. The ilevel requirement for both dungeons is 226 which is greater than the questing and dungeon gear from Wrath of the Lich King. Before the patch, if you were leveling up via dungeons, you had to stop and quest for a bit at level 80 in order to get the ilevel of gear required to continue running instances.
Quartermaster Iris Moondreamer at the Nordrassil Inn in Hyjal sells full sets of gear for each class. In Vash'jir, Erunak Stonespeaker saves you from drowning and then sells the same gear as Iris. The beginning quest reward gear in Cataclysm is ilevel 272, so questing for a while will get you better equipment, but these new vendors help close the gear gap.
Note: If you are choosing to buy your gear from Erunak, make sure to do so before completing the quest chain that gets you out of the sunken ship. as he stops being a vendor in the next phase.
I had missed this detail in the patch notes so it was a pleasant surprise when questing in Hyjal on a mage that had leveled the previous 20 levels via pet battles and archaeology. Though the gear gap isn't as large between the older expansions, I'd still like to see more supply vendors like these and the ones in Pandaria as you level up, particularly if you are doing so in a non-traditional way.