also the IIS7 documentation sucks
http://msdn2.microsoft.com/en-gb/library/aa965182.aspx
Usage:
<httpRedirect enabled="true"
exactDestination="false"
httpResponseStatus="Temporary">
<add wildcard="*.asp"
destination="aspx.aspx" />
</httpRedirect>
call test.asp -> will show: aspx.aspx/test.asp
possibel values for httpResponseStatus are : Temporary, Found, Permanent.