Here is the post in the Daz Forums

http://forum.daz3d.com/viewtopic.php?t=136197

You have to be a Platinum Member as the offer seems to be only posted in the Members Forum.  It says that if you purchase Carrara 7 or 7 Pro or upgrade from 6 / 6 Pro that you will get a free update to Carrara 8 (same Pro or Standard version that you bought upgraded).  The extra discount apparently is on Platinum Members.  I show the Plat price for upgrading from 6 Pro to 7 Pro at $99.93 even if you bought a Platinum Membership for one month it would still be an excellent savings.  

I should clarify in my posting above that the free upgrade is for those who purchase 7 standard/pro or upgrade to 7 standard/pro (the one in the Magazine being C6 Pro that can be upgraded) who are Platinum members during this special.  I wasn't clear and wanted to make sure it didn't sound like those who have 7 will get a free upgrade to 8.