What did Hu Jintao really mean?

Depends on who you ask, apparently. Let's take a look at a couple of contrasting reports:

Xinhua: Hu Jintao: "Taiwan independence" activities doomed to fail

"The 'Taiwan independence' activities have run counter to the Chinese nation's strong will to safeguard national unity. Such activities will get nowhere and are doomed to fail," Hu told political advisors attending the first annual full session of the 11th National Committee of the Chinese People's Political Consultative Conference in Beijing....
"We are ready to have exchange, dialogue, consultation and negotiation with any political parties in Taiwan, as long as they recognize that both sides of the Taiwan Straits belong to one China," Hu stated.
"The negotiation will be conducted on an equal footing with completely open topics -- there is nothing we can't talk about," he added.

So, no budging on One China, and no softening up on the anti-Taiwanese independence rhetoric. Basically, a repeat of regular policy statements.

But Reuters gives a more friendly headline: China offers talks with Taiwan on equal footing

Chinese President Hu Jintao offered broad peace talks with self-ruled Taiwan under its "one China" policy on Tuesday, weeks before the island elects a new president, but Taiwan rejected Beijing's conditions.

Hu also reached out to pro-independence politicians, saying China would welcome them if they shifted their stance.

It's interesting that Reuters seems to think this is some kind of new or generous offer. Both candidates responded, with Hsieh making the first statement, saying:

"I believe [anything that promotes] peace is good. But from our position there should be no preconditions. We should be able to discuss any issue. I think in cross-strait relations each side should be able to say their piece, and then put controversy to one side. We should not disrupt and delay the things that we can do because of the things we cannot do."

That's just restating the DPP's official position for the last eight years.

Ma responded, cleverly avoiding any reference to the One China issue at all, and instead tried to be seen as defending Taiwan:

"President Hu says he is willing to speak with those who have advocated independence, and that is no bad thing. But we should point out that it is China's suppression of Taiwan on the international stage that has caused many people to lean towards Taiwanese independence. Many people have only chosen this path because of what they feel is a lack of dignity accorded to them. So I think this cause and effect is something the Chinese authorities should be very clear about," said Ma.

Good spin, of course, and certainly people in Taiwan react badly to China's suppression of Taiwan, but the fundamental issue is that Taiwanese want to have the right to control their own destiny and do not want to be subject to Chinese rule. Taiwanese control over Taiwan's destiny is something the CCP openly opposes, that the KMT clandestinely opposes, and only the greens openly defend. However, since the greens spend so much time whipping up nationalist sentiment with vague references to sovereignty before the election instead of focusing on the fundamental issue -- who's right it is to decide Taiwan's future -- they can't get much political leverage off of it.