Two options specified on the enum (first parameter) find by OBID or UID returns IObject.
Dim lobjItem As IObject = SPFRequestContext.Instance.QueryRequest.GetObject(GetObjType.ByOBID,lstrOBID)
This method has been enhanced to search in order. First the cache, and then datatables based on your domain scope (that is, adminobj, dataobj, and so on). If it does not find anything, it will then search the relationship tables for a matching item, and then finally it will search the cache for a matching item.