Below is the basic progression map. Obviously your mileage may vary, i.e. If you're Paragon or Premonition you will be able to skip some of the below and/or mix and match at your discretion.

*Normal Dungeons/Crafting/Questing to get full set of 85 blues (non-heroic) to do Heroic dungeons.
*Heroic dungeons to get full set of 85 Heroic blues to do Normal mode raids.
*Normal raids to get full set of 85 epics (non-heroic) to do Heroic mode raids.
*Heroic Raids to get full set of 85 Heroic epics, which will presumably help a bit on Sinestra and the next tier (when released with patch 4.1.0)

*Badge vendors to help fill in gaps at all tier levels.

*No real gating to speak of for ship.

*Sinestra opens after Cho'gall is defeated on HEROIC mode. No timers or attempt limits, but she will pound you relentlessly. She has better than Heroic epic level gear (half a tier better).