It is likely that the enmity towards Ramadan, despite his explicitly moderate message of tolerance and inclusion of muslims within the political and cultural mainstream, stems from his unwavering critiques of Israel's human rights abuses towards the Palestinians:
"What I'm saying as a Muslim is that when I criticize a policy, for example the Saudi policy or the Egyptian policy, I am not Islamophobic," he said.
"And when I am criticizing the policy of the state of Israel, of [Prime Minister Ariel] Sharon, I'm not an anti-Semite. It's just a political criticism."
That's not unfamiliar territory to me. His (Israeli-hyper-partisan) detractors such as Robert Spencer insist that Ramadan is a closet anti-Semite, though Ramadan has explicitly denounced anti-Semitism as an alien import to the Muslim mindset, urging Muslims to take heed of the moral tragedy of the Holocaust.
It's a tragic irony that the muslims most critical in bringing about cultural change in the Middle East and elsewhere, the potential saving bulwark against the rising tide of extremism, are lumped in with those they denounce. The reason is their refusal to denounce being muslim itself. Apparently, the only "acceptable" muslim is one who rejects the Qur'an as a divine text, Muhammad SAW as a prophet of God, and adopts a secular-fundamentalist approach to their "faith". Some are comfortable with this, others are not - count me among the latter. Tariq Ramadan is a hero to me and others like me who will always be a muslim and yet will not cede our right to be counted among the Men of the West.
UPDATE: via Brian Ulrich, I just discovered the blog Chapati Mystery, which also addresses the Tariq Ramadan issue in a nice post with useful links to more info on him via Muslim WakeUp! and Abu Aardvark.