Get list if users currently logged into SQL Server

set nocount on
create table #sp_who (
  spid        smallint,
  ecid        smallint,
  status    nchar(30),
  loginame    nchar(128),
  hostname    nchar(128),
  blk        char(5),
  dbname    nchar(128),
  cmd        nchar(16),

  requestid integer)

)

insert into #sp_who execute sp_who
select distinct loginame from #sp_who
drop table #sp_who