Don't kill the messenger...
I've got nothing to gain from relaying this information. My contact at Apple is a long time friend and he's got nothing to gain by giving me this information. Believe me or not, this informations probability for being fact is significantly higher than most of the other posts regarding product delays, which are usually just someone's speculation, or at best, an educated guess.
Someone else referred to me not having any 'proof', and its true, I didn't record the conversation, but how about a small wager? I've never heard or read anything about new iMac designs. If new iMacs are announced and they have Aluminum enclosures, you doubters out there owe me an apology. Fair enough?