The new 5 man dungeons will help to introduce the Deathwing Raid.
The current plan with the Deathwing raid is to have it all available immediately upon release.
The Deathwing raid will be smaller than Ulduar with many phases or encounters with Deathwing.
Patch 4.4 will bring a world event before the next expansion.
The next expansion should be released with a "meaningful difference" in the release timeline compared to previous expansions.
A new Darkmoon Faire