Just wanted to point out something in the documentation that may need to be updated -- likely just a copy/paste or formatting error.
Eloqua Profiler Configuration Guide for Salesforce.com
The direct method of creating the VisualForce page specifies this markup; however it leads to an error page in the Profiler VF page on the lead/contact profile.
<apex:page standardController="Lead"> <apex:iframe src="https://secure.p03.eloqua.com/apps%2Fprofiler%3FemailAddress%3D{!lead.email}"/></apex:page>
Removing the escape characters in the SRC tag, like below, and it worked.
<apex:page standardController="Lead"> <apex:iframe src="https://secure.p03.eloqua.com/apps/profiler/index.aspx?emailAddress={!lead.email}"/></apex:page>
May be obvious or not, but hopefully this can save someone else a few minutes of time trying to figure out the problem.