A comment from http://sci.esa.int/rosetta/
Jonathan McDowell says:
16/07/2014 at 19:39
Fred - as you know we have a proprietary period on Chandra too but I think for planetary encounters it's a bit of a different situation. I think it would be a reasonable approach to release in real time jpg images with no metadata - which you can't do publication quailty science on - and keep the science grade data proprietary. (Actually I personally feel we should do this with Chandra and other missions too).
Last images they published are 5 days old. New ones should now be much better. What the...!
Do they find the images embarrassing? Does the comet not look like a rubble pile which they have always said that it is? Are there jets?