I'm loathe to quote wikipedia but in the absence of a better explanation that doesn't involve an EU directive (see a few pages back)
http://en.wikipedia.org/wiki/Capital_requirement
Regulatory capital is a buffer. If the buffer is used up, deposits are at risk. Until it is used up, then they aren't.
The current situation is that the liquidity issue appears to have been addressed by Govt guarantee. This didn't address credit worries in the UK which forced UK Govt to underwrite equity investment to bolster the main banks capital buffer.
I still think it is likely that this will have to happen in Ireland sooner rather than later, despite people like Eugene Sheehy saying he'd rather AIB died that do an equity offer.
So, in summary, possible that depositors could lose if defaults were sufficiently catastrophic, in practice unlikely as Government would be forced to intervene well before capital buffer was exhausted.