While the 30-ton transformer has been fixed, a large spill of helium occurred because at least one of the 1,700 superconducting magnets failed.
The event known as "quench", caused by a faulty electrical connection between two magnets, heated up roughly 200 magnets in the sector 34 (the last sector that was just being commissioned) by 100 °C. The vacuum may have been lost in parts of the pipe, too.
This story will delay the LHC at least by two months (needed to warm it up, fix it, and cool it down again; update: sorry, at least until Spring 2009): Special CERN announcement, Thaindian, FoxNews, New York Times. The LHC alarmists may enjoy several additional days of life. :-)
The problems are disappointing but surely not unprecedented. The LHC's predecessor in the same tunnel, LEP, was nicknamed "Lots of Extra Problems" because many things broke at different stages of the project.
This is LHC, Les Horribles Cernettes, about liquid nitrogen, not helium, but you may get the idea anyway. :-)