There are no significant problems and obstacles with the design and the CPU won't be delayed till 2008. This is AMD's horse to run as the firm knows that it needs a lot more than K8 dual core to fight the upcoming Conroe. The new Intel desktop CPU is due to arrive in just thee days from now and is getting ready to win most of the benchmarks versus Athlon X2 5000+ and the FX62.
AMD traditionally doesn't tell everything to its motherboard partners and very few of them knew about the 4x4 platform before the last minute. I guess it is the same with the K8L quad core as AMD wants to catch Intel dozing and to take its crown back one more time.
So the quad core is definitely due earlier before 2008, I can tell you that.
Here is the Digitimes story. µ