With this caveat, Eric Kleefeld puts up the latest Zogby at TPM:
I think the better course is to follow the polling summary at pollster.com.
The new Zogby national poll gives Barack Obama a huge lead over Hillary Clinton for the Democratic nomination, with 52% to her 38%. The internals show the two tied among women voters, with Obama winning men by about two to one — consistent with his Wisconsin win last night.
The poll also shows Obama to be a much stronger Dem nominee against John McCain:Obama (D) 47%, McCain (R) 40%
McCain (R) 50%, Clinton (D) 38%
There is one caveat, though: Zogby's polls for the state races on Super Tuesday showed significant error in Obama's favor. On the other hand, the internals of this poll match up pretty well with the Wisconsin exit polling.