No. They're not emo. The lyrics may be emo-ish but the music isn't. Hybrid Theory and Meteora were considered Nu Metal.

Chester Bennington explained that the sound of Minutes to Midnight will have the nu metal element discarded. The album will be a mixture of punk, classic rock and hip hop beats. The howling and growling will also be abolished. Their first single What I've Done was pretty good! Makes me want to buy the album!

Additionally Minutes to Midnight will also be the first Linkin Park album to have the Parental Advisory: Explicit Content warning.

Source: Wikipedia, Minutes to Midnight (album)