See thread at http://groups.google.com/group/liftweb/browse_thread/thread/184b7eb51d461b30

I've found what looks like another CSS selector bug. The selector is
appending the attributes of the input element to the attributes of the
root output element. This is especially problematic when on of those
attributes is id :-)

This is with lift-2.4-M4 and scala-2.9.1. From a console:

    scala> import net.liftweb.util.Helpers._ 
    import net.liftweb.util.Helpers._ 
    scala> val input = <div id="foo">content</div> 
    input: scala.xml.Elem = <div id="foo">content</div> 
    scala> val selector = 
         |   "#foo" #> ((ns: xml.NodeSeq) => <wrapper>{ns}</wrapper>) 
    selector: net.liftweb.util.CssSel = // snip 
    scala> println(selector(input)) 
    <wrapper id="foo"><div id="foo">content</div></wrapper>

You can see that wrapper is mistakenly getting an id attribute. The
final output should be <wrapper><div id="foo">content</div></wrapper>