According to the PubMed website today: "PubMed has been designated to be maintained with minimal staff during the lapse in government funding. The information on this website will be kept as up to date as possible, and the agency will attempt to respond to urgent operational inquiries during this period. Updates regarding government operating status and resumption of normal operations can be found at http://www.usa.gov."
However, the National Library of Medicine is now shut down. Since the MEDLINE database is what both PubMed and EBSCO MEDLINE are based on, new data entry will probably also be on hold. Interlibrary loans normally available from collections of government libraries will not be available, so costs may increase on some requests.