While the coupling via the property market between Anglo and the others is somewhat plausible, my most paranoid fear is that Lenihan has been informed of the real situation in Anglo and the true nature of its balance sheet is that it is in a far worse state than we (or the even the markets) suspect. He has decided, for political and financial reasons, that winding-up Anglo would simply be too expensive. In other words Anglo is not of systemic importance to Irish retail banking but is of systemic importance to the public finances.
If this is the case, it is a nightmare situation. Not only would it constitute almost criminal reckless behaviour on the part of a finance minister to pour public money into an insolvent bank but it would also be quite scary what it would say about how deep a hole Anglo (and the exchequer via the debt guarantee) is in. It's all speculation, of course, but I've read of talk of injecting between 1 and 3 billion to keep Anglo going. If paying 1-3 billion is preferable to paying for a wind-down, then the exchequer exposure must be of the order of many many billions of euro.