Converting strings with internal delimiters into lists

Hi UserRs,

I know that there has to be an easy way to do this in
R (probably easy enough that once someone clues me in
I'll smack myself on the forehead for not figuring it
out myself), but my searches on my own have not
yielded any hints.

I have many fields in my dataset that participants
entered as "free lists" - i.e., the field constitutes
a varying number of names each separated by a
delimiter.  The resulting data frame might look
something like:

testtable<-
as.data.frame(cbind(c("Joe,Mary,Jane","Mary"),c("Fred,Joe","Pete,Joe,Mary,Fred")))

In actuality the names are typically multi-word
organization names, but you get the idea...

What I need to do is to convert these text strings
into lists comprised of the elements separated by the
commas so that I can work with these elements across
the dataset, manipulate them, etc.

Thanks in advance to any kind soul who can offer me a
tip to the appropriate functions or a line of code!

Best,

Shelby