I still think this is the single greatest holiday screenshot I have ever captured.
Noblegarden is one of WoW's less stressful holidays overall -- which is good, as you'll have to deal with Children's Week later in the month. Noblegarden will run this year from Sunday, April 8 (this Sunday) until Sunday, April 15 (well, technically Saturday at 11:59 pm server time, if your calendar reads the same as mine). If you've never done Noblegarden before or only done its pre-2009 version, be aware that Noble Gardener (the holiday's meta) is part of the year-long What A Long, Strange Trip It's Been achievement rewarding the 310% speed Violet Proto-Drake.
The one new thing that I can confirm in 2012 is the presence of the Swift Springstrider, which can be purchased for 500 (!) Noblegarden chocolate from holiday vendors or found randomly in eggs. (However, nobody knows what the drop rate is like. I would bet on "bad.") This is pretty much the same deal as the Swift Lovebird from Love Is In the Air -- it's a way to keep players who already have the meta involved with the holiday.