Ireland needs foreign investment to prosper and continue to grow but I don;t think that the irish people voting against the Lisbon treaty will affect this.
The only negative aspect of that I can see is that some companies will see Irish people as more aware and inquistive than other countries and might see that as a problem in employee's. IE, we are not blind sheep just following orders....
The big multi nationals come to our Island for a few reasons I can see, our low corporate tax rates, our young educated workforce, the english language ( like it or not! ) and the Euro. I see none of these changing with the implementation or rejection of the treaty.
The only thing I can see costing us jobs at the moment ( apart from corrupt bankers, here and in the US where it all started and our politicians consistantly bad decisions ) is our wages costs, we in Ireland are paid a large amount for our time and that affects foreign investment. Take Dell for instance, they have clearly lost business by moving most of their call centre to India but they have lowered their wages costs so much that their p&l sheet is up... simple economics
Companies don't care about politics or people, they care about share prices and windfalls. The IDA did a great job getting companies here but developers put house prices up and then peoples wages had to go up, so then everyone started to put prices up as people had more money and their suppliers put the prices up ect. ect. ect. this spiralled upwards to the property crash and now we have the situation we are in