Try Dawn of War (1, not 2). Although, they were released ever so slightly before 2008. Still great games though - for a starting point in that series, skip right to Dark Crusade, where a playable campaign with all races was introduced (it's a standalone game, not really an expansion pack. You won't miss anything with the original Dawn of War and it's first 'expansion') The game will be dirt cheap now and insane value for money. Game has some an innovative gameplay with resource and base building, and combat gameplay is fantastic. Dawn of War 2 has dropped the typical resource gathering and base building, so steer clear of that one unless your into deep squad based tactical gameplay (its hard to label as a true strategy, really)
Bro, this may be an abstract suggestion, but how about the Medieval 2 total war and shogun 2 total war. Sick games with a turn-based strategic map and awesome 2000+ troop battles, need a decent gaming system i guess. IMAGINE THAT! Commanding 1000+ soldiers, feels like a real commander. Starcraft series is the best by far, especially battle.net playing online, fighting with other dudes is so cool. Havent played starcraft 2 but i remember the good ol days of starcraft 1 with sunken defense and tank defense.
Company of Heroes is a must have RTS. Age of Mythology is also fantastic, especially if you liked the Age of Empires games. StarCraft 1 and 2 are amazing. Warcraft 2, old one now but was so much fun back in the day. (you'll need DOS box to get it working). Close Combat 3: The Russian Front Close Combat 5: Invasion Normandy
If you like old school RTS games then Starcraft II is you best bet, design wise it is very 1990's - but updated with modern graphics (I assume that is why you requested 2008 - 2012?). The games tend to last between 10 minutes (if you're crap) to 40+ minutes.
Supreme Commander 1 and 2 bring the genre up-to-date. Both games have their sets of fans, I prefer SupCom 2 v2.5 over the first, but massive battle fields offer a lot of scope for new tactics. The games last a lot longer too - 3-4 hours on a map if everyone knows what they are doing.
If you don't mind older games (2004), then Rise of Nations is a must. Old school style, resource gathering, it mixes Age of Empires with Civilisation perfecty. Having your enemy suffer attrition while in your territory adds a new dynamic to the strategies that I have yet to see in any other RTS.
you really should try ForgedAlliance (standalone expansion to Suprem Commander), you wont find a game with more stragetic deepth more informations about this here: www.faforever.com and a video about it here http://www.youtube.com/watch?v=TxkIhwcMkgU
I'll wholeheartedly support Sheppard there, FA is the greatest game I ever played. Ever. Period. Nothing else even compares to its scale and competition I think it can be bought for pence now on steam too...