For our technology previews, I normally set up an email address and a discussion forum. Though feedback through the email address seems to be more popular, feedback through the forum allows everyone to see both the question and the answer.
Though the forum is preferred, some users who use the new Internet Explorer 9 browser to post to the forums are getting blank posts. The web team is looking into it. Until a solution is in place, users can always fall back on email.
Repair work is alive in the lab.