我可以使用Silverlight UI从Silverlight应用程序验证用户吗？

我问过一些MS员工这个问题（在PDC和现在的MIX），大多数答案都是"应该很容易"的答案。 然而，我被指示在论坛中询问没有人知道该怎么做。

这是我想做的事情：编写一个具有用户名和密码框以及一个登录按钮的Silverlight应用程序 当用户单击"登录"按钮时，我想点击Windows Live ID WCF服务（或HTTP服务或其他）来验证用户。 我想找回一些基本信息，例如用户的显示名称和我可以存储在我的应用程序中的唯一ID，以便将偏好设置与此用户关联。

所以，我所要做的就是不编写我自己的用户数据库（或使用  ASP.NET）。 我希望任何拥有Windows Live ID的人都可以登录我的网站并开展业务。 

任何人都可以帮助我指明正确的方向吗？ 

附：我承认Windows Live ID和Windows Identity Foundation之间存在混淆。  我刚刚参加了MIX会议，编写了身份驱动的Silverlight应用程序，这一切听起来不错，除了似乎没有办法将所有的好处与Windows Live ID。 编写自定义提供程序是有道理的，但这正是我想要避免的。 

I've asked a few MS employees this question (at PDC and now at MIX) and most answers have been along the lines of "that should be easy".  However, I was directed to ask in the forums as nobody had details on what to do.

Here's what I want to do: write a Silverlight application that has username and password boxes and a Login button.  When the user clicks the Login button, I want to hit a Windows Live ID WCF service (or HTTP service or whatever) to authenticate the user.  I want to get back some basic info such as the user's display name and a unique ID I can store in my application to associate preferences with this user.

So, all I'm trying to do is not write my own user database (or use ASP.NET's).  I want anyone with a Windows Live ID to be able to log into my site and get down to business. 

Can anyone help point me in the right direction? 

P.S. I admit confusion between Windows Live ID and Windows Identity Foundation.  I was just in the MIX session on writing identity driven Silverlight apps and it all sounded good except that there does not appear to be a way to link all that goodnes with Windows Live IDs.  Writing custom providers makes sense but that's what I'm trying to avoid.