We installed an update to the Classify Web service on June 11 that resolves the standard number searching problem we posted about previously. ISBN searches (E.g., http://classify.oclc.org/classify2/Classify?isbn=9780425260753) are now working as expected.
If you're not familiar with Classify, it's a handy way to add base LC or Dewey call numbers to a record. You can also use it to get FAST subject headings. Check it out and then don't be shy - let us know if you have questions.