That's two polls this week in which Giuliani's overall support has declined. It's also interesting that in February of 1999 Bush was consistently polling in the 40s and had shown steady growth. Giuliani's support has been stuck in the mid 30s since November.
With the field split as many ways as it is, as early as it is, that's still very significant. Gingrich and McCain have absolutely no chance, so their numbers will have to go somewhere. If Rudy only pulls 1/3 of each withdrawn candidates' numbers, he'll be able to carry the day easily.