I was working on a similar thing this morning to practise my XML parsing this time with XML::Parser.
Things to note:
There is appears to be a seperate node for XML feed of Newest nodes called Newest Nodes XML Generator. Clicking on XML link in Newest Nodes doesn't seem to do much.
If you are hovering around a network like I do you could use the Win32::Message module to do the equivalent of Net send <username> <message>
I wouldn't want to poll the link to heavily to add undue burden on the servers. I wonder if and interval of 5 minutes would be enough. This is of course if you are on a Win32 network. I don't know what the equivlent is on a predominately unix network. (Probably because such broadcasts are evil ;-)