I couldn't find anything newer, either. One does have to wonder how no usable supportive research was generated in 20-odd years of the first edition, though:

http://ies.ed.gov/ncee/wwc/interventionreport.aspx?sid=56

It does appear that the 2nd edition addresses one of the flaws of the 1st, which was the complete absence of practice with standard algorithms, or math fluency.

...pronounced like the long vowel and first letter of the alphabet...