Could someone share the serial? 
The serials are on the download site - but a new information:
it is most probably not legal to use this version but the reason for the free download (not: usage) is that Adobe shuts down their activation servers for cs2, thus regular customers cannot activate their purchased products anymore. The solution: Publish generic serial numbers and installation packages that don't need to be activated.
So to sum it up: The fact that this is downloadable for anyone (probably someone screwed up) doesn't mean it can be used legally, at least that's my current information. It's just like taking away a product from a store because the cashier is having a break.
All sites saying otherwise are just copying information, just like all the 6d "review" blogs... Adobe is not in the habit of giving away their premium products, just like Canon doesn't give away free 5d2 bodies.