I have short hair, and I still colour it. I just don't use a terribly dark colour - so go for a shade lighter than I'm after, iyswim?
I just dye it with a normal hair dye (last one I used was Clairol Perfect 10, and the colour was the best it's ever been).
It depends what colour you want. If you want a significantly lighter colour, than your own hair, then yes - it will show quicker.
I don't have to dye mine very often, probably once every 11 - 12 weeks (may have to be longer this time, as I've just had my ears re-pierced). My hair is quite grey now, but still the colour lasts.
I disagree with the comments about highlights if your hair is grey. The 'theory' behind this, is as you age & your hair beomes grey, you become paler too, so lighter or highlighted hair is supposed to be more flattering than the colour of your youth.
Last year I had my hair highlighted as I was pregnant (I was 41, and couldn't go for 9 months with grey hair - highlighting seemed a safer option). The lighter colour didn't suit me, at all - I look younger with darker hair.
Whilst highlights should last longer than 'block' colour, and fade more evenly, I do think you will have roots showing quite quickly. A colour closer to your natural colour will give you more mileage.