daz - the reason Airbus were not happy with MOL faxing Boeing the details of Airbus' offer is probably down to
a) What is often referred to as "commercial confidentiality", and
b) Airbus would have expended a lot of wasted time and effort on putting together a deal with Ryanair, meaning that they had less time to spend on airlines that were serious about buying from Airbus
Commercial confidentiality is the concept that if you want me to tell you lots of commercially sensitive non-public information that my rivals would like to hear, then I expect the information to be treated confidentially and for you not to dislose it. In a similiar way, if a company has many employees, the staff expect their boss not to tell everyone else in their team their salary.
As for b), how do Airbus know that if they spend time in 2011 putting together a deal with Ryanair, that Ryanair will actually treat it seriously and not just use it as a negotiation tool with Boeing and then tell Airbus to get lost. In effect, are Ryanair just being timewasters, or are they really serious about buying 300 A320-family aircraft ?
If you tell Ford the details of the offer on a huge fleet of 100,000 cars that Vauxhall were offering (remember that a 737 is worth over 1,000 times that of a car), you may well find that Ford improve their offer and you go with Ford. If you need to buy some more cars five years later, and in the meantime the fleet salesmanager at Vauxhall finds out what you did, then Vauxhall will be much less interested in talking to you - in effect Vauxhall may tell you to either pay full price for their cars or stop wasting their time.