UA 40 on Oct 8. Left the gate on time. Noticed we were spending a lot of time revving engines before starting to taxi and I knew it was not good news. Back to the gate, total delay was 4 hours, Once back at the gate they did let pax off but demanded you take your "stuff" with you...Fortunately for me we were sitting in row 2 so we just waited it out. Delay after delay after delay. They did hand out bottled water too...whoopie. Yes, I know you can't fly on a broken airplane but when there are something like 7 or 8 delays it gets frustrating.