Both mine often sit in the street for more than a month at a time, there really is NO problem whatsoever - and this is *definitely* preferable to other people driving your cars (esp. leadfoot nutters ;-) .
Who knows what one person driving the car hard without letting it warm up will do? - You can be sure a lot more damage than leaving the car to sit.
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black