If you want to use it with groups, you can use:
library(plyr)
mydata<-mtcars
ddply(mydata,.(carb),colwise(sd))
carb mpg cyl disp hp drat wt qsec vs am gear
1 1 6.001349 0.9759001 75.90037 19.78215 0.5548702 0.6214499 0.590867 0.0000000 0.5345225 0.5345225
2 2 5.472152 2.0655911 122.50499 43.96413 0.6782568 0.8269761 1.967069 0.5270463 0.5163978 0.7888106
3 3 1.053565 0.0000000 0.00000 0.00000 0.0000000 0.1835756 0.305505 0.0000000 0.0000000 0.0000000
4 4 3.911081 1.0327956 132.06337 62.94972 0.4575102 1.0536001 1.394937 0.4216370 0.4830459 0.6992059
5 6 NA NA NA NA NA NA NA NA NA NA
6 8 NA NA NA NA NA NA NA NA NA NA