Zerg

It seems that the Protoss have received most of the attention so far in terms of development. Judging from the gameplay videos (make sure you download the hi-def video), the Protoss have a well-rounded force at all tiers.

The races will remain the same: Zerg, Terran, and Protoss. You can view a video of the Protoss ultimate battleship - the Protoss Mothership.

It's a bit of speculation at this point but the tiers look something like this:

Tier 1 

Protoss Zealot - the mainstay of the Protoss ground forces hasn't changed much, except for getting a Charge ability to get him close distances faster.

Tier 2 

Protoss Immortal - Immortals get through heavy hitters like the Terran Siege tanks so if you expect the Terran to go mass tanks, Immortals will be a good strategic option.

Protoss Phoenix - dubbed as a air-supriority fighter, the Phoenix seems to be a counter to Mutalisk rushes. The Overload ability allows it to fire at all nearby enemies which makes it perfect to stop Mutas from destroying your expansion.

Protoss Stalker - Stalkers excel at hit-and-run tactics. Their Blink ability not only gets them to a higher/lower ground in a … blink, it also allows them to massacre running units (e.g. CSVs). In that respect they are similar to their Dark Templar brethren.

Protoss Colossus - Technically, the Colossus will probably be Tier 3 but I see a lot of players teching quickly to get him as early as possible. It looks like it replaces the Reaver unit which failed its role as a ground support unit in Starcraft. Most Protoss players didn't use it except for harassment via drops.

Tier 3 

The Colossus seems to have a much better potential to support the Zealots. His ability to move to lower/higher ground means the harassment potential is still there… I bet it'll go through a dozen Drones in 5 seconds.

Protoss Warp Ray - the demo pitted Terran battlecruisers against Warp Rays. The four rays destroyed 3 battlecruisers without a single loss. These will be a mid-/late-game answer to massed heavy units as their attack increases the longer they shoot at their target.

Protoss Mothership - you can only build one of these and Blizzard calls it the Ultimate Protoss weapon. It has three specials - one defensive, two offensive ones. My guess is once you build one, it's GG for your opponent. It's a like the finishing move in Mortal Combat.

Starcraft 2: Protoss Units | Zerg Units | Terran units