Well, beside the information on the phoenixNet site, not much actually.
Here's the FAQ from
http://home.phoenixnet.com:
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Q: Why do I need PhoenixNet?
A: Whether you're new to the Internet, or a seasoned pro, you may not know all the great, essential products and services that are available to help you. Plus, it's a real chore to find, access and install these tools if you don't know where to look. PhoenixNet makes it simple. We show you the best
Q: How does PhoenixNet decide what tools to offer?
A: PhoenixNet carefully selects the best-of-breed products and services from respected technology manufacturers.
Through a careful review process, PhoenixNet determines what type of tools and services would be most valuable to our users. Then we select the best providers of these products and enter into partnerships with them in order to provide these tools directly through our network, usually for free. We are always forming new partnerships and adding to our service in order to meet the needs of end users worldwide
Q: What's it going to cost me?
A: All of the tools offered on PhoenixNet are free. All prices for services or goods, if any, are clearly indicated in the descriptions of the tools during the selection process.
Q: How does PhoenixNet work inside my PC?
A: The PhoenixNet Internet Launch System (ILS) is a patent-pending technology built into the firmware of your PC. PhoenixNet's technology resides safely within ROM (Read Only Memory). PhoenixNet is activated automatically at the initial launch of your new PC.
Q: Can I use my PC while PhoenixNet is downloading my tools?
A: Yes! While PhoenixNet is downloading your new free tools, you can multitask and continue to use your PC's other programs -- and even surf the web.
Q: What if I want to discontinue using the PhoenixNet resident application?
A: That's easy. You can disable or enable PhoenixNet at any time with a right-click on the PhoenixNet tool tray icon.
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Basically what this thing does is updating the system with 'critical' upgrades, adding new tools and more stuff.
BTW on the FAQ page there are some system requirements listed:
* Microsoft® Windows 98
* 16MB RAM
* Internet Explorer 4.x and above
* 28.8 Kbps (minimum) Internet connection
So if you're running Linux/BeOS or another non-Windows OS, you're safe?