For reasons related to the United Kingdom's position on freedom of movement of persons and to the common travel area between both countries, neither Ireland nor the United Kingdom participate in the Schengen process. Now that the Schengen process is to be brought into the EU framework, the two countries may, if they wish, continue not to take part. Either or both, however, will also be able to opt in to all or part of Schengen, subject to certain conditions.
Protocols added to the EU and EC Treaties, and a declaration made by Ireland annexed to the final Act, taken together, make it clear that Ireland's concern is to maintain the common travel area between Ireland and the United Kingdom in order to maximise freedom of movement of persons into and out of Ireland; and that, subject to this, Ireland would wish to participate to the maximum extent possible.
I am not aware of any proposals to change existing arangements for passport controls between Ireland and states which are part of the Schengen system.