I thought the last paragraph of the El Reg article said it all:
The incident appears to be isolated, but it once again highlights concerns about BT and Phorm's claims for the security of their interception technology, and their ability to operate it to specification.
When will you be trialling BT Webwise?
BT is commencing trials of BT Webwise on 30th September 2008. We will be inviting a small proportion of BT's consumer broadband customers to take part in the trial. The trial involves only BT Retail consumer broadband customers; it does not involve customers of BT Business, BT Ireland or other BT-owned ISPs, such as PlusNet.
"Oops, we made a technical error and Plusnet users were included."
# BT Webwise does not collect or store any personally identifiable information.
# BT Webwise ensures users' browsing remains anonymous by using a random-number cookie to link to each computer.
# BT Webwise doesn't keep records of individual websites that you visit or what you were doing on the web.
Given the level of incompetence BT/Phorm have exhibited today (they couldn't manage to exclude plusdsl2.net in spite of the concerns flagged up about this in the past), can we really trust those statements from BT regarding privacy?