After inspecting the CCTray application and the logfiles on my server, I finally found the undocumented URL for this XML document with the status: http://buildserver.local/XmlServerReport.aspx.
After this quest for XML, I only needed an XSLT to get the results. So here it is:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output method="xml" encoding="utf-8" indent="yes" omit-xml-declaration="yes" />
<xsl:template match="/">
<table border="0" cellpadding="0" cellspacing="0">
<thead>
<th style="text-align:left;">Project</th>
<th> </th>
<th style="text-align:left;">Status</th>
<th> </th>
<th style="text-align:left;">Last buildtime</th>
<th> </th>
<th style="text-align:left;">Buildlabel</th>
<th> </th>
<th style="text-align:left;">Activity</th>
</thead>
<tbody>
<xsl:apply-templates select="/CruiseControl/Projects/Project"/>
</tbody>
</table>
</xsl:template>
<xsl:template match="Project">
<tr>
<td class="ms-vb" align="top" nowrap="nowrap">
<xsl:element name="a">
<xsl:attribute name="onfocus">OnLink(this)</xsl:attribute>
<xsl:attribute name="href">
<xsl:value-of select="@webUrl"/>
</xsl:attribute>
<xsl:attribute name="onclick">GoToLink(this);return false;</xsl:attribute>
<xsl:attribute name="target">_self</xsl:attribute>
<xsl:value-of select="@name"/>
</xsl:element>
</td>
<td> </td>
<xsl:element name="td">
<xsl:attribute name="class">ms-vb</xsl:attribute>
<xsl:attribute name="align">top</xsl:attribute>
<xsl:attribute name="style">
padding-bottom: 3px;
<xsl:choose>
<xsl:when test="@lastBuildStatus='Failed'">
color:red;
</xsl:when>
<xsl:when test="@lastBuildStatus='Exception'">
color:red;
</xsl:when>
<xsl:when test="@lastBuildStatus='Unknown'">
color:yellow;
</xsl:when>
<xsl:when test="@lastBuildStatus='Failed'">
color:red;
</xsl:when>
<xsl:otherwise>
color:green;
</xsl:otherwise>
</xsl:choose>
</xsl:attribute>
<xsl:value-of select="@lastBuildStatus"/>
</xsl:element>
<td> </td>
<td class="ms-vb" style="padding-bottom: 3px;" align="top">
<xsl:value-of select="substring-before(@lastBuildTime,'T')"/> 
<xsl:value-of select="substring-before(substring-after(@lastBuildTime,'T'),'.')"/>
</td>
<td> </td>
<td class="ms-vb" style="padding-bottom: 3px;text-align:right;" align="top">
<xsl:value-of select="@lastBuildLabel"/>
</td>
<td> </td>
<xsl:element name="td">
<xsl:attribute name="class">ms-vb</xsl:attribute>
<xsl:attribute name="align">top</xsl:attribute>
<xsl:attribute name="style">
padding-bottom: 3px;
<xsl:choose>
<xsl:when test="@activity='Building'">
color:red;
</xsl:when>
<xsl:when test="@activity='CheckingModifications'">
color:yellow;
</xsl:when>
<xsl:otherwise></xsl:otherwise>
</xsl:choose>
</xsl:attribute>
<xsl:value-of select="@activity"/>
</xsl:element>
</tr>
</xsl:template>
</xsl:stylesheet>
Now you need only to configure a custom XML Webpart to load the xml from your buildserver, set the XSLT and the title of the webpart.
