Normally, you wouldn't think it would take a lot of arm twisting to get someone in that situation to accept a hundred billion or so, but as has been pointed out, this is a loan and interest will be due as well as principal. And there will also be plenty of strings attached, the exact nature of which are deliberately obscured for political reasons. In any case those strings will probably change with events.
The European Union has of course immediately approved the Irish government's request.
Lost on no one is a) the fact that the Irish banks have in the last few weeks run out of anyone willing to lend to them, except the European Central Bank itself; b) investors now consider any number of European countries shaky debt risks, Ireland included; and c) that the biggest holders of Irish bank paper are German and British banks.
Put another way, what is going on is a roundabout bailout of bad loans from German and British banks to Irish ones, funded by the richer countries of the EU. Meanwhile, the richer countries (Germany, primarily) can claim they're merely coming to the rescue of Ireland in its hour of need. Oh, and of course, the EU will need to take a bit more control of Irish finances...just to make sure that hundred billion credit line is being used wisely.
All this because the last hundred billion euro line in the sand-- across Greece--didn't stop the credit markets figuring out and acting on the dodgy state of finances across the peripheral countries in the Eurozone. There aren't too many more places to draw lines: Portugal is next, and can plausibly be bailed out, but if Spain or Italy ever come to need a bailout, the game is up. Their budgetary holes are too big for even the German taxpayer to fill.