The Open Group's DCOM implementation wasn't open source. Also, MSRPC/DCOM is just an RPC layer, the real value/lock-in was in the protocols built on top of them

The Open Group's DCOM implementation wasn't open source. Also, MSRPC/DCOM is just an RPC layer, the real value/lock-in was in the protocols built on top of them, such as Active Directory. dcerpc.org has a maintained version of the OSF DCE RPC runtime (this bounced around from the FreeDCE project, to PADL, then Novell, Likewise and now Apple).