I to had the MAK the first time i fired up my Tivo and wondered how. i went to buy the Desktop plus key but it would not let me add it to my account as it had no record of the HNP being brought.
I sent emails to the Support people in Aussie (you buy the HNP and Desktop Plus Key from Aussie) and was told that after an upgrade had been done in the States to the Tivo Backend it then allowed all Tivos that got activated to get the MAK with out paying for it. They also told me that anyone that got it that had not paid for it will have it removed from their Tivo once the bug was fixed.
In the end I just brought the HNP and got them to refund my money on the extra Desktop Plus Key as you get one with the HNP.
I dont use the Tivo software to stream my stuff to it i use pytivo but this still requires you to have the HNP
see below for the email i got from Tivo
Thanks for your email and we apologise for the frustration and confusion.
TiVo Inc US has recently performed maintenance, including to the system that supplies the Home Networking Package and the Media Access Key, and, as a result, some customers who have performed TiVo activations since this maintenance have erroneously received a Media Access Key without purchase and activation of the Home Networking Package. We are working on rectifying this issue and the Media Access Key will be removed from all accounts which have not purchased the Home Networking Package.
To further confuse the issue, the way customer purchase and access the Media Access Key in New Zealand (and Australia) is different to in the United States. In the U.S. TiVo is sold with a subscription (which includes the Media Access Key) but they must pay US$14.99/month which is why you were able to download TiVo Desktop from the US website. In Australia and New Zealand the TiVo media device is sold outright and with no monthly subscription and therefore the Home Networking Package is sold as an optional accessory for AU$90. As you are probably aware in the U.S. the Desktop Plus Key must be purchased for an additional US$24.95, whereas in Australia and New Zealand one Desktop Plus Key is included in the Home Networking Package.
For more information on our pricing policy, please click here: http://www.mytivo.co.nz/buy/onlinedirect/pricingpolicy/