On behalf of Adobe Systems Incorporated …
You have heard wrong! Adobe is absolutely not providing free copies of CS2!
What is true is that Adobe is terminating the activation servers for CS2 and that for existing licensed users of CS2 who need to reinstall their software, copies of CS2 that don’t require activation but do require valid serial numbers are available. (Special serial numbers are provided on the page for each product download.) See http://forums.adobe.com/thread/1114930.
You are only legally entitled to download and install with that serial number if you have a valid license to the product!
So it isn’t free. But there’s nothing stopping you logging in and obtaining both a full installer and serial number, this just made things easier for Adobe.
Alternatively, they should’ve just waited for CS2 users to post on their forums and refer them to their customer support for a serial number exchange. Easier still, it can’t be too difficult to keep a web-based service that allows existing users to enter a license key, check it looks legitimate and then spew out the new key? It just seems really lazy.