Patients may have had up to four prior chemotherapeutic regimens; steroids alone and local radiation do not count as regimens (radiotherapy must have been completed at least 14 days prior to starting vorinostat); Rituxan alone does not count as a regimen; however, Bexxar or Zevalin do; for treated patients, the most recent therapy must have failed to induce a complete response (i.e., there is persistent disease by CT or PET), or there must be disease progression or recurrence after the most recent therapy