IBM have a bunch of products that implement/support CORBA (AIX, SuperPoseidon etc.) They also support RMI-IIOP (as part of Websphere as Kyle points out). DCOM is not an open standard, like the other two, so is proprietory MS only. IBM have taken the more pragmatic route of using existing open standards to implement their product set rather than specifying one of their own. But that being said, IBM have a huge product range including I'm sure some old/unusual IBM-only distributed computing method.