As an actual function you could do:

create or replace function getSysdate
return date is

  l_sysdate date;

begin

  select sysdate
    into l_sysdate
    from dual;

  return l_sysdate;

end;
/

Which you could test in SQLPlus as:

TEST>select getSysdate() from dual;

GETSYSDATE
----------
2010-01-04

Not sure why you would want this versus just having sysdate in your code. The Oracle date datatype includes the time portion.