I have not been following the Giro as closely as the Classics or as I will follow the Tour de France. But I thought it could be useful to mention the very well made website of the Giro, which even offers a free live webstream of the event.
Another interesting find (via the Inner Ring Blog) is the Road Book for the race, normally not made public but which for the Giro is available as a pdf. The level of detail is quite astonishing, with information on road surfaces for the finish for example, and main features of the stage. I wish Road Books were always made available for races!
Update: I almost forgot to mention that two of my favourite bloggers are writing about the Giro, one at Universal Sports (Cycling Inquisition, who signs as Klaus on U.S.) and another at Bicycling Magazine (Bike Snob NYC who signs as, well, BikeSnobNYC). Really worth reading!