@peterash - RE: Just the email field is unstyled now
CF7 now uses the new HTML5 input[type="email"] for the email tag. When you updated the CF7 plugin your email fields may have changed from input[type="text"] to input[type="email"].
The CSS in your current WordPress theme probably does not cater for this new HTML5 email input field.
http://contactform7.com/faq/#Why_does_my_email_address_input_field_look_different gives some guidance on how make these fields look the same in your current WordPress theme.
Use Firebug or Chrome Dev Tools to understand the CSS used for your CF7 form elements.