If you are talking about ORF files, I have about 13,000 that I have had in Lightroom from version 1 on. I have not, however, upgraded to version 4 of Lightroom, so I can not state that it supports them but I doubt if Adobe would have dropped support for ORF files.
By the way, my camera is an E-1.
See the attached site for the full list of supported cameras.
Not all ORF files are the same, just like all of Nikon's NEF files are different when coming from different cameras. Each new Olympus model that comes out requires some work by Adobe engineers to support the ORF files that camera produces.
LR's working with a particular flavour of ORF doesn't imply that it will work with a different flavour. You really have to find the camera model in question in the Adobe list of supported cameras to know that its raw files are usable by Lightroom.
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