I noticed that if you took Zogby's last poll before Iowa and added 13 for momentum you came up with very close to the final results. (I added Dean and Gephardt's totals and subtracted 13 and also came out very close to the final result.)
Zogby
Kerry 24 +13=37 (final result 37.6)
Edwards 18 +13=31 (final result 31.8)
Dean+Gep 42 -13=29 (final result 28.6)
Have I discovered a mathematical prediction apparatus for a caucus state? :-)