It also looks like you can't insert another column for each row returned by the INSERT INTO ... EXEC.
For example, this gives me an error:
CREATE TABLE #mytemptable
myserverrole VARCHAR(50) DEFAULT @@SERVERNAME
insert into #mytemptable
exec sp_helpsrvrolemember @srvrolename = 'sysadmin',
@mycheckdatetime = getdate
select * from #mytemptable
(I realize the code is pretty bad; c/p and messing with it until I get what I want then I figure out what I did and clean it up.)
It says, "Procedure or function sp_helpsrvrolemember has too many arguments specified." I tried getdate() but it didn't like the () and when I removed the () I realized it was because it thought I was passing parameters into sp_helpsrvrolemember.