In polls after polls, since 1970 elections, the PPP either wins or gets second highest numbers of votes a lot of times--all across Pakistan! So the 5000-10,000 bloggers here and elsewhere probably constitute less than the number of CASTED votes in one National Assembly seat.
Now, this is not a defense of Gilani. It is just to point out the disconnect between the 'masses' versus the media perception.
As to why Gilani is willing to go prison? Well, he was chosen for his 'loyalty' to Zardari. Gilani chose to remain in prison for several years instead of getting on with Musharraf's govt. when several other PPP stalwarts joined Musharraf. Coming from a powerful, wealthy family and to resist the 'offers' made to him (certainly a Cabinet post) he chose the prison. He was noticed. And he was chosen as the Prime Minister.
PS. PPP needs to get rid of these feudals like Gilani, Zardari etc. But that needs to happen along with an overall evolution of Pakistan. Short of that---perhaps an Iran-like Mullah revolution or even a Bolshevik Revolution?