I too received an e-mail urging me to vote for this song, although not from republican friends. I even heard people on the radio urging us to vote for it, just to stop 'Candle in the Wind' from winning!. Its just that it seems to appeal to the Irish sense of humour to subvert polls such as this. I remember that at the end of 1999, Time magazine was holding a poll on the person who had the most impact on the 20th century. I received e-mails urging me to vote for a guy called Ronny O'Brien. Ronny was a young Irish soccer player who had been signed up by Juventus in Italy, but who had never got to play a match with them (and still hasn't!). I believe that Ronny was doing very well in the Time poll until the organisers disqualified him.
Anyway, from looking at the BBC top 10, it appears that most of the songs were there as the result of a campaign.

Stephen