All I can say...
Grab that 0w-30 castrol syntec bottle (yes the one with the red markings and lettering) and look at the back. It should say something like "made in Germany" near the UPC bar code. This has nothing to do with identifying the dating of the blend as far as I know.
Now flip the bottle upside down and there should be a printing in white letters, for whose first digits will read the "born on" date. I don't have a bottle with me now, but I seem to recall a letter followed by two digits denoting the year. Another thread spoke of how to make further sense of it, and could probably be found in a GC section search with something like "date".
As far as color, yes the '04 blend is green and from what others have said is sweet smelling...something like "gum bears". It appears that the '05 blend has changed to gold and lost the sweet smell, but I noticed someone recently made a comment that on a more recent '05 date, that the color switched back to green.
Well, color is color. But honestly, it's the rest of the add pack and base oil that needs to handle the task of protecting the engine and giving proof by a good UOA report...like any other lubricant in the business.
Will the newer stuff put the older stuff to shame, or will we not see the likes of the '04 batch again here in the states for some time? Perhaps a marketting catch... Just have to wait and see as the miles collect and UOA's are compaired.