This time it's the Soyo SY-P4S and retail boxed P4 1.7GHz for $249. The items are itemized on the receipt as:
P4 CPU $125
If you compare those prices to pricewatch, the Retail P4 CPU is $65 less than the best price online (and excluding the usually rip-off shipping charges, which makes this an even better deal). And the motherboard is $30 less than the cheapest one online (again excluding shipping which is no cheaper than sales tax).
It looks like my local store is running out. They had one stack of boards left tonight when I went back, compared to a few rows on the top shelf this morning.
I have returned portions of combos before at Fry's with no problems at all, as long as I have the original receipt and the item is not opened.
edit: the sale first appeared in Friday's ad and is good through tuesday.