I wrote this one quickly so if it needs some modification or you run into issues please let me know. This script will only return information if you are both attached to an Analytic Workspace/OLAP Multidimensional Datatype and are executing SQL. If both of these are not satisified you will return no information.

For Standalone Instances

set pages 500 lines 110

col usn format a20 heading "USER (SID,SERIAL#)"
col awn format a20 hea "OLAP AW"
col sql_id format a13
col sql_text format a40 wrap

select username||'('||sid||','||serial#||')' usn, daws.owner||'.'||daws.aw_name awn, vses.sql_id, sql_text
from dba_aws daws, v$aw_olap vawo, v$aw_calc vawc, v$session vses, v$sql vsql
where daws.aw_number=vawo.aw_number and sid=vawo.session_id and vawc.session_id = sid and vses.sql_id=vsql.sql_id
group by username, vses.sid, vses.serial#, daws.owner,daws.aw_name, vses.sql_id,sql_text
order by username, sid, daws.aw_name;

USER (SID,SERIAL#)---OLAP AW------------- SQL_ID------- SQL_TEXT
-------------------- -------------------- ------------- ----------------------------------------
OLAPTRAIN(128,23945) SYS.EXPRESS--------- c2t583nkt79m3 select count(product) from cb$sales_cube
OLAPTRAIN(128,23945) OLAPTRAIN.SALESTRACK c2t583nkt79m3 select count(product) from cb$sales_cube

For Real Application Clusters

set pages 500 lines 110

col usn format a20 heading "USER (SID,SERIAL#)"
col awn format a20 hea "OLAP AW"
col sql_id format a13
col sql_text format a40 wrap
col inst format a11 hea "INST(#)"

select username||'('||sid||','||serial#||')' usn, gvinst.instance_name||'('||gvses.inst_id||')' inst, daws.owner||'.'||daws.aw_name awn, gvses.sql_id, sql_text
from dba_aws daws,gv$aw_olap gvawo, gv$aw_calc gvawc, gv$session gvses, gv$sql gvsql, gv$instance gvinst
where daws.aw_number=gvawo.aw_number and sid=gvawo.session_id and gvawc.session_id = sid and gvses.sql_id=gvsql.sql_id
group by username, gvses.sid, gvses.serial#,gvinst.instance_name,gvses.inst_id, daws.owner,daws.aw_name, gvses.sql_id,sql_text
order by username, sid, daws.aw_name;

USER (SID,SERIAL#)-- INST(#)---- OLAP AW------------- SQL_ID------- SQL_TEXT
-------------------- ----------- -------------------- ------------- ----------------------------------------
OLAPTRAIN(128,23945) orcl(1)---- SYS.EXPRESS--------- c2t583nkt79m3 select count(product) from cb$sales_cube
OLAPTRAIN(128,23945) orcl(1)---- OLAPTRAIN.SALESTRACK c2t583nkt79m3 select count(product) from cb$sales_cube