Must people have already mentioned what I'm going to say, but I'll summarize anyways. THG's data may be sound, but it is very misleading in its presentation. A lot of this is because of inclusion of Netbursts models that shouldn't really be included like the 840EE.
Virtually all 90nm chips have now been end of lifed including the 5xx series, the 6x0 series, the 8x0 series, all Netburst Extreme Editions, and the 920D, 930D, and 940D. The "official" Intel product line up is the $93 805D, $113 820D, the $133 915D, the $163 945D, and the Conroes. All the other models may still be available, but they are not "preferred" models anymore and are therefore overpriced. Those overpriced models are the ones skewing the data and making it look like Intel doesn't have anything competitive in the under $400 segment.
In actuality 90nm single cores are going to be cleared out as 805Ds or 820Ds, while 65nm Netbursts are being cleared out as 915Ds and 945Ds. With Intel's dual die approach single cores can be cleared out twice as quickly along with regular dual core stock. Now the price points for those 4 Netbursts are very competitive even though they are Netbursts. For one the 805D is under $100 which is a dual core in Celeron D and Sempron territory. The 915D is definitely slower than the X2 3600+, but it has the advantage of being cheaper at $133 to $148, and also being available right now. The X2 3600+s primary target is China and will be made available in other markets as availability allows. Also, it's important to note that the 915D will be replaced with the 925D on October 1st at the same $133 price point which should better put pressure on the X2 3600+.
Now it's mentioned that the E6300 is overpriced right now, but that's fine because it can easily compete against the X2 4200+ and X2 4600+ at $200. But what will compete against the X2 3800+? That's the job of the 945D. At $163, it's $4 more expensive, but the average performance of the 945D is higher than the X2 3800+ so it works out quite well. (Yes the X2 3800+ will be faster in games, but slower in other areas.) As well, the initial 945D versions are C1 stepping, but a newer D0 stepping is arriving which should allow lower power consumption considering a 3.6GHz 960D now has a 95W TDP instead of 130W. The X2 3800+ still consumes less power, but the gap isn't as large anymore. That all makes the 945D quite competitive against the X2 3800+.
Essentially, the reason why Netburst stock will continue to clear is because of those 4 models that I mentioned which offer decent performance considering their price. Intel's next round of price drops come October 22 where the 915D will drop to $113, the 820D drops to $93, and the 805D is discontinued. (The 925D will remain at $133). With these 4 Netbursts holding their own in the under $200 segment, Intel has bought time for Conroe to be overpriced initially until stocks rise. Besides E6300 and E6400 availability is very good right now so prices should drop quickly after the higher models are finally available.
A decent price performance comparison is here:
http://www.xbitlabs.com/articles/cpu/display/core2duo-shootout_13.html
The prices are based on "ideal" manufacturer prices, but the performance and power numbers should be accurate so you can just translate the data points across the price axis to the market price. For example, you will see that even if the E6300 sells for $195 as Zipzoomfly prices it, it'll still beat the price/performance between the X2 4200+ and the X2 4600+. Also $195 is only $12 more than Intel prices it which is perfectly acceptable given the demand.