serial port - How to "reset" an Arduino board? -

i've uploaded sketch arduino uno loop this:

void loop(){     serial.println("hello world"); } 

so, now, can't upload anymore, because ide says "port in use".

is there way "reset" arduino without programmer?

edit :
nothing else using serial port, , went fine until uploaded previous sketch.

edit :
i've found interesting things:

• problems 0021 on ubuntu 10.04 lucid lynx
• re: problems 0021 on ubuntu 10.04 lucid lynx
• uno sending serial data becomes un-connectable serial monitor

try following:

1. prepare basic empty program (empty setup, loop, etc.)
2. compile it.
3. reset arduino using hardware button on chip
4. press ctrl + u upload code.
5. if unsuccessful - got 3.

there delay before boot loader starts programs, work on timing. worked me when bug in arduino's code executing soft reset every 500 ms.