As it says, If I have a dot com domain name and my country is .ie, will google not pick my site for keywords if it is checked through google.ie. Hope I explaned that right.
I see a lot of .com results when I search in http://www.google.ie/ .ie domain would be better if your business is strictly Ireland based. If the .ie domain is available I would suggest you to grab it right away. Develop two sites maybe...
I agree that you would have an easier time getting rankings on google.ie with a .ie domain. You can still get good rankings with a .com though. Just focus on getting a lot of links from other Ireland based websites.
If you have a domain with .com and don't have .ie domain for which you have to do SEO. This thing is not bad for SEO at all. Start your SEO work.