Here is what I got using ruby 1.6.6 on Linux:

In a file:

rich@puff:~/ruby$ ruby commatest.rb 
"~, More"


In IRB:

irb(main):001:0> x = "\"CommaTest, After\", More"
"\"CommaTest, After\", More"
irb(main):002:0> x.gsub!(/\"(.*),(.*)\"/,"#{$1}~#{$2}")
"~, More"
irb(main):003:0> p x
"~, More"
nil

So in my case, it was the same output, but not the same as 1.7.2!  :)

-Rich