The local Sensis branch is closed, so I had to call the 1800 number.
Sensis staff now have a Fiddler capture from me that proves that the redirect is occurring, they have my cell phone number, and my email address, and they have information about my various blog posts about this incident.
Now we wait and see how long it takes Sensis to respond and take down the dangerous advertisements, and what they will do to minimise the chance of this happening again in the future.
Update: See the comment by a Sensis employee here. It seems the malicious advertisements have been pulled; I'll continue to monitor the situation.
I've just had a look and the Flash advertisements can still be accessed via the direct URLs, and they are still hijacking users if displayed. I haven't seen them displayed at whitepages.com.au but will continue to monitor the situation. I'll be happiest when those advertisements can no longer be accessed, even via direct URL.