I've been able to watch live baseball for the past three seasons on NASN. However, NASN never got the rights to the World Series, which is annoying. They generally show the games the following day when the results are known. The rights to show the games live are held by Channel 5, which is not available in Ireland.
Well, now we have some progress. Setanta Sports (free to all NTL subscribers) is showing the World Series live. That means all baseball fans in Ireland with NTL can watch the World Series, not just those who subscribe to NASN. The games don't start until 1am, but you can set the video if taped coverage is good enough for you.