It seems that you can save the price of 1 year Microsoft AppHub membership if you are a Nokia Launchpad member and an Ovi Appstore Publisher.
If you use the same email address that you used to register with Nokia Launchpad to register for a one-year membership for Apphub, the $99 price of the membership will be returned to you.
The Apphub is the main site, where you can register to publish apps to the Windows Phone 7 Marketplace or to xbox360, a one-year membership costs $99 dollars. So if you are planning to develop and publish apps for the Windows Phone 7 platform then it is time to take the chance and register for free.
Here is the information from Nokia:
We are offering a free Microsoft App Hub registration for the first one year to those Nokia Developer PRO and Launchpad members who are registered Ovi publishers in the countries that Microsoft supports on the App Hub. This offer will save you $99 USD (the regular annual membership fee) as the membership fee will be refunded to you by Microsoft. The membership will give you access to submit applications for Windows Phone Marketplace as well as access to the developer tools, documentation, code samples and forums.