Spell Haste has been a very hot topic since it was announced that it will decrease the global cooldown in Patch 2.4. Where most of my interest lies regarding the change is whether or not it will have a significant impact on Affliction Warlocks and their end-game raiding DPS. Some seem to think that with faster, less spread-out DoT applications, a Warlock will be able to throw in another Shadow Bolt or two before it would be time to refresh, therefore increasing damage output by a decent amount. Others, however, don't believe the change will add up to much of a DPS difference at all, and are looking forward to more tweaks that would better help the Affliction tree in end-game.
Two threads worth reading on the matter are HERE and HERE, with the first doing a bit of theory-crafting about the changes and it's impact on Affliction while the second asks why Spell Haste doesn't speed up DoT ticks and offers up some valuable responses.
I'm sure this topic of discussion isn't going to go away anytime soon, so expect more info to be incoming at any time. =)