Rte Dtt

According to the following document (Word) "Status for the implementation of DVB-T in the CEPT area June 2004" downloadable from the European Radiocommunications Office (http://www.ero.dk/) here with other info.

Ireland (30-06-2004)......In DTT, transition period planning for the 12 main stations, 18 major transposer stations is completed and a further 14 transposer stations is also complete. Co-ordination discussions relating to the provision of services in the transitional period at these sites are completed. It is likely that the new plan for the bands at RRC-06 will be established before DTT services commence.

RRC-06 (for planning of the digital terrestrial broadcasting service in parts of Regions 1 and 3 in the frequency bands 174-230 MHz and 470 -862 MHz) will complete its work in June 2006. (A related ComReg document is available here)

So in answer to your question based on the above info its looking like late 2006 - early 2007.

If this delay happens it may not be such a bad thing because the H.264/AVC video (MPEG-4 Part 10) and High Efficiency Advanced Audio Coding (HE-AAC) audio codecs have now been forwarded to ETSI for standardisation to the range of codecs that may be used in DVB applications which will allow greater compression per multiplex (i.e. more channels per multiplex) and the possibility of HDTV. The standard could be incorporated into DVB-T receivers by the time the Irish DTT service launches.
The current Irish standard, Video (MPEG 2 Main Profile, Main Level,), Audio (MPEG 2 layer I and II,) depending on Carrier Modulation (QPSK, 16QAM or 64QAM) will allow between 4 and 8 TV channels per multiplex similar to the UK DTT service.

France is currently considering if it will use MPEG-4 for its DTT pay TV service.
Blu-ray and HD-DVD high-capacity discs have MPEG-4 / AVC as a mandatory standard.

Regards