This week’s Nature includes a brief paper that concludes that multicellular life originated about 100 million years earlier that previously known. The work places sponges in the Cryogenian period, >635 million years ago, prior to the Ediacaran period. See Flies & Bikes for more on this paper. Formally, of course the paper suggests that either demosponges were there, or an ancestor – but still, more evidence of the antiquity of life on Earth!
Love et al (2009) Fossil steroids record the appearance of Demospongidae dueing the Cryogenian period. Nature 457; 718-723. doi:10.1038/nature07673 (subscription required)