Community Server Feed Reader Fails in Medium Trust Level

[UPDATE: see this new post here Custom Trust Level For Community Server]

I just installed Community Server 2.1 SP1 for a client. I had been told that it would run in Medium trust, so I tried that setting. Unfortunately, in Medium trust, adding feeds gives the following error:

Add Feed Error

The problem is the same as discussed a while back in this thread. And apparently it was not fixed in 2.1 or 2.1 SP1.

Here is my solution:

In web.config, I added this element to <system.web>

<trust level="MediumWithWebServices" originUrl="" />

Taking advantage of this simple fix requires you to have first followed the steps listed in this article:
Customizing Trust Level Policy. The steps are not specific to Subtext, even though the article focuses on Subtext. The exact same approach works for Community Server or probably any other ASP.NET 2.0 Web application.