The Google Webmaster Central team has made some changes to a couple of the website verification methods in Webmaster Tools. Here's what you need to know:
Meta Tag Verification - Previously, this had to be associated with an email address in your Google account. Obviously, changing email addresses could pose verification issues. Now, the meta tag verification does not require an email address.
HTML File Verification - The change here has to do with the use (or lack thereof) of 404 error pages for non-existent URLs on websites. Websites that didn't use 404s couldn't use the HTML file verification. Just upload the new HTML file that Google Webmaster Central provides for verification.
If you're using third-party software or sites that upload the meta tags or HTML files for you, be sure to check if they've updated to work with the new methods.