Slight tweaks to dpkendal's script. Gives the BBEdit document a name (rather than "untitled <integer>", and skips the \n to \r stuff, which I don't think is necessary in recent versions of BBEdit.

gistfile1.scpt

tell application "Safari"
	set _source to do JavaScript "window.document.documentElement.outerHTML" in document 1
	set _name to name of document 1
end tell


tell application "BBEdit"
	make new text window with properties ¬
		{contents:_source, source language:"HTML", name:"Generated source: " & _name}
	select insertion point before character 1 of text window 1
	tell window 1
		activate
	end tell
end tell