For example:
$(elementid,top.document).attr(attributeName)
or
$(elementid,parent.document).attr(attributeName)
And don't forget document.domain = "yourdomain.com" before running $(selector, parent.document) because I ran into "access denied" issues just like location.href for iframes
document.domain = "yourdomain.com"
$(selector, parent.document)
location.href