Robbie just tweeted an hour or so ago that he will not be riding the Giro - more at his website.
And, there's apparently an article at a Kazahk site (google translation here) which claims that Astana's financial difficulties continue and that if they finish the Giro it might be the team's last race. (found via DPF). That adds some intrigue to the whole question of "who will Astana's leader be at the Tour?" - guess the question shifts to "will Contador and Armstrong be able to ride the Tour at all?".