Radio contact with ESA's XMM-Newton X-ray Observatory was lost on Saturday 18th October. Ground-based optical observations have verified the observatory is still in one piece and in its expected orbit, and ESA's 35m radio antenna in Australia has detected a weak radio signal from the satellite. Workers at ESA's European Space Operations Centre (ESOC) are attempting to command the spacecraft to recover a working communication system.
Read the full news item at ESA's website.
I hope they manage to recover from this problem. There is a vast amount of science that (the astrophysical community) XMM-Newton is best suited for and that can not easily be done using the other existing X-ray observatories (Chandra and Suzaku).