Ireland has vetoed the Lisbon Treaty.

Or has it? What is a veto? More particularly, what is a veto in the European Union?

Ireland has previously cast a veto (in the EU Council of Ministers) and it was denied that it had that effect. That is, it was treated as a dissent, not as a block.
See HERE for details.

The defeat of the Referendum on the Lisbon Treaty in Ireland is not a rejection of the European Union. However, the response of the European Union may indeed lead to a rejection of the EU. Only a Union based on law can attract and hold the allegiance of the people of Europe. The legal basis of the European Union lies in the treaties. Under the treaties Ireland’s assent to the Lisbon Treaty is a requirement to bring it into force.

To say that implementing the Lisbon Treaty was “going to be difficult” as Christine Lagarde the French Finance Minister did in Korea is to imply that the European Union is not an entity built on law.

To press ahead as President Sarkozy and Gordon Brown propose is to subscribe to the same implication. To propose a “two-speed” Europe (see HERE) is a proposal to abandon the European Union, a legally questionable idea.