Sick Squid
Not sure of any specific aviation sites, but it has been a
huge problem over the past couple of weeks. I read somewhere that in the 48 hours preceeding the invasion of Iraq around 50 sites were attacked and/or defaced and in the following 24 hours around 1000 were targeted.
There were rumours around the middle of last year that several hacking groups had joined forces and were gearing up for more high-profile attacks. I won't mention the names on-list - but you can get more info from looking at the examples in the following F-Secure article.
F-Secure article