The current state of the Democratic primary may be best analogized to a tennis match. Hillary was 'serving' last night, with Obama having a chance to 'break' her in the symbolic states of Massachusetts and California, and to have a close result in New York. None of those occurred, which means that Hillary held.
This weekend has a somewhat uncertain expectation game in Louisiana, where the first presidential primary since Katrina (with all of its attendant population movements) will be held, together with caucuses in Washington State and Maine.
It's then on to the 'Chesapeake Primary' next week (Maryland, Virginia, DC) all on February 12th, which is at this point, seen an Obama 'serve.' But Hillary will be back on serve on March 4th, when Ohio and Texas vote, both seen as natural states for her because unions and Latinos, respectively.