Mass Effect 2 - Preview @ 1UP and Kotaku

After releasing Dragon Age: Origins, Bioware has moved into preview mode with its upcoming game Mass Effect 2. Previews have appeared on both Kotaku and 1UP.

Both previewers have had hand-on experience with the game. The previewer for Kotaku mentions this about ME2's no-overheat system for weapons:

Gone is the first game's system of infinite-ammo weapons that overheat if used to much too quickly. Reader feedback to that possibility was mixed during PAX. The EA representative who showed me the Omega mission couldn't tell me what the narrative justification was for abandoning the series' no-reload-needed ballistics technology. He could tell me, however, was that the game's developers felt that the old system for regulating player's use of guns - an overheating mechanic that enforced slower shooting and mandatory cooldown - disrupted the flow of a good firefight. Players would run for cover and wait until their weapon was ready to fire again. Not anymore. Hopefully.

The 1 UP reviewer mentions that for the Xbox 360 version, you can now give individual commands to your teammates. 

Mass Effect 2 also brings over the PC version of Mass Effect's ability to give individual movement commands to squadmates. Instead of the original ME's general "everybody go, no wait, everybody stay put" command scheme, you can now use the D-pad in combination with your crosshairs to order buddies to move to specific areas. 

Voodo Extreme features a 9 minute sequence from the game, while a video developer's diary can be found at Destructoid. 

Avoid if you don't want to be spoiled. Note that some of this footage also can be found in the youtube video Dhruin posted.