As noted here, CMS started observing LHC beam splash events for the first time in 2009 on Saturday evening (Geneva time). What is happening here is that a beam is sent into a collimator upstream of the CMS detector, resulting in a spray of particles that then go through the detector, lighting up a number of components. Such splashes are happening again this evening. (Accelerators usually do their best stuff on the weekend, when there are fewer people tinkering with things.)
Darin Acosta, one of the detector operations leaders, has been posting interesting news from the detector as it comes in — follow him here. Of course there is much further to go yet, but there is a lot of excitement in CMS as we end our fourteen months of patience and preparation and start detecting beam particles once more.