Concept art for Devastator & The Fallen has been released by ACToys. Although the final rendering in the movie may be different, it gives an overall idea of what to expect.

 

The above Decepticon is Devastator. As previously revealed in last scene of the teaser, that Constructicon was huge... Now imagine the shear size of Devastator if it consists of 6 such Constructicons transformed together!!

Head: Mix Master – Concrete Mixer Truck

Torso: Demolishor - Terex O&K RH 400 Hydraulic Mining Excavator

Right Arm: Rampage - Wheeled Front-load Shovel.

Left Arm: High Tower - Crane

Right Leg: Long Haul -  Dump Truck

Left Leg: Scrapper - Bulldozer.

 

& here's The Fallen. As confirmed in the first pic, there'll be 3 main villains in Transformers 2 - Devastator, Megatron & The Fallen. The poster is indeed that of The Fallen.
The Fallen looks more insect-like than the rest of the Decepticons. So how will they develop The Fallen's story around the Pyramids (SG-1?). ;)

 

How do you expect these tiny little guys to stand up against the monsters. That's some unseen footage from Chevrolet showing up all of the Autobots in the film.
They also released the names & the vehicles of each character:

SIDESWIPE – a stylized Corvette vision concept vehicle [Stingray concept]
SKIDS and MUDFLAP – twin AUTOBOTS based on Chevy's Beat (a concept that will go into production as the Chevy Spark in 2011) and Trax concepts
JOLT – an AUTOBOT-based on Chevy's upcoming Volt extended-range electric vehicle

BUMBLEBEE, the heroic AUTOBOT based on Chevrolet's Camaro concept from the first "Transformers" movie, returns with a high-performance attitude. Joining the vehicles on stage will be BUMBLEBEE in his AUTOBOT form, standing almost 17 feet (5.2 meters) tall and 13 feet (4 meters) wide.

 

Don’t forget there’s also Optimus Prime (Peterbilt truck), Ironhide (GMC Topkick C4500), Ratchet (Hummer H2 Search & Rescue) & Jetfire (SR-71 Blackbird).

Who said 13 is unlucky? Tomorrow on Friday the 13th, obviously at Friday The 13th release, the trailer for Transformers: Revenge of Fallen will be released! :D