Cross your fingers that this latest revelation is another Yes Men hoax. [update 1: I’ve confirmed that this was NOT a Yes Men hoax]
[update 2: Guardian is now reporting  the story]
A draft copy of a confidential memo to the UNFCCC Secretariat has surfaced here at the Copenhagen climate talks that has some pretty disturbing analysis. The memo dated December 15, concludes that at this point in the climate talks:
“Unless the remaining gap of around 1.9 to 4.2 Gt is closed and Parties commit themselves to strong action prior and after 2020, global emissions will remain on an unsustainable pathway that could lead to concentrations equal or above 550ppm with the related temperature raise around 3 degrees Celsius.” [my emphasis]
Here’s a screenshot, you can download the 4MB PDF version here: leaked UNFCCC secretariat document. 
In layman terms this means that if the developed nations, like the US, Canada, Germany and France don’t commit to deeper emissions cuts at the talks underway in Copenhagen we’re screwed.
Based on the best scientific research, experts in the field have concluded that in order to avoid the most catastrophic effects of climate change, we need to stabilize carbon emissions at or below 350 parts per million.