Sending webform submissions to email with csv export of submissions
As tenken wrote, Webform module has a function for that, namely webform_results_export

Do you really want a single line of CSV e-mailed when a form is submitted, rather than periodic downloads?  You could modify your e-mail template to print each value, comma, value, but it wouldn't be an attachment.  If you absolutely need an attachment some custom code and/or Rules is the way to go.