Is this email a scam?

[#1]

I received the following email from apparently nominet
Dear Registrant,
As part of our systems improvement programme we are making some important changes to the way in which you access your domain name account.  We are withdrawing account security questions in favour of an optional 2-factor pass phrase.  The pass phrase will work in conjunction with customer user names and passwords.
You are a user of the security questions feature in our Online Service and we wanted to make you aware that we will be withdrawing this service on 11 October 2011.
We recommend that you set up a secure pass phrase for accessing your account which will give you additional security and will help to keep your account and domain names safe.  If you would like to set a secure pass phrase for your account please log in to our Online Service and select add/change passphrase from within your Account Settings page.
If you have any questions about these changes to our log-in process please contact our support team on 01865 332244 or email nominet@nominet.org.uk.
Many thanks for your attention to this matter.
Kind Regards,
Nominet Customer Services
support@nominet.org.uk

I have never had any direct connection with nominet, but I do remember when PN had a number of their customers' email accounts hacked, PN set up a domain name (which PN maintain) to allow a new email identity for me.
Peter

[#2]

If any email doesn't address you by name, it is not from the alleged source.

[#3]

And I take it you have never registered a .uk domain.

[#4]

I believe that the email may be genuine, it contain no links and the email addresses and telephone number are for Nominet
If you do a Whois http://www.nominet.org.uk/ on the domain that Plusnet registered for you I believe you will see your postal and email addresses.

[#5]

I doubt very much that you will - it should just give your name

[#6]

All the domains that I have registered have my address and one of them was registered by PN as a freebie after the email spam problems. Can't remember which one as I moved it away from PN as I wanted better control of the DNS entries.

[#7]

Mine says
    Registrant's address:
        The registrant is a non-trading individual who has opted to have their
        address omitted from the WHOIS service.
and this one was a Plusnet freebie

[#8]

Mine says the same but I am sure that I had to opt out via the Nominet web site (to make sure my address was not listed)

[#9]

up to recently mine had my full details, so asked Customer service, and it was changed the following day

[#10]

Mine is a Plusnet freebie and like Jim's  it contains no personal details.
I didn't have to opt-out (didn't even think about it until now).

[#11]

Not a scam e-mail.  See http://www.nominet.org.uk/registrars/systems/Plannedchanges/releasenotes/september2010/

[#12]

Whether or not your address details etc. visible is dependent on whether or not you've opted out. You may not have been asked for your preference when you registered the domain if it was done manually by a support agent.
Other TLD's like .com, .net etc. don't support this feature in the same way although you'll find some registrars will offer it as a (normally paid-for) feature.
The email from the OP's post looks genuine to me.