This entry is part 18 of 19 in the Bash-whacking series
sudo apt-get install librsvg2-bin
for i in *; do rsvg-convert -a $i -o `echo $i | sed -e 's/svg$/png/'`; done
 

to rasterize the svg at 300dpi, shrinking dimensions by 50%:

for i in *; do rsvg-convert -z 0.5 -d 300 -p 300 -a $i -o `echo $i | sed -e 's/svg$/png/'`; done