I was at a seminar at the National Library in Dublin yesterday when Cartriona Crowe of the National Archives gave the latest update on the digitisation of the 1901 census.
It seems there have been some problems (no surprises, there!) but the records will go online before middle of June and they will be released in one fell swoop, not in tranches as the 1911, and with full search facilities under all fields. However, in order to meet that schedule, the records will be released without a full check having been performed. So we should expect more initial errors and omissions than the 1911 had.
In other words, the 'early' 2010 of the original estimate of release was optimistic. The 'mid' 2010 might just be met!