Splitting a string into a vector of strings

[Thom Burnett <Thom.Burnett@cognigencorp.com>]

What's the quick and easy way to make
a <- "AB, ABC, FG, HIJKL, M"
into

b <- c("AB", "ABC", "FG", "HIJKL", "M")

I haven't yet seen this at all using match , scan, regexpr, etc.
I know that I can locate the ',' and then loop to call substring but 
that seems unecessarily complicated.
Thom