In the public discussion about whether or not Prince Harry should serve in Iraq, an analogy is often made to his uncle, Prince Andrew, flying helicopters in the Falklands war. It's a false analogy, for two reasons.
Firstly, Andrew was serving in a British-led and -manned force - Harry would be serving in a multinational force that is, ultimately, led by the Americans.
Secondly, Harry is far more constitutionally significant than Prince Andrew ever was or is. Andrew was the third of the Queen's four children. In March 1982, when Argentina invaded South Georgia, the Queen was, it appeared, still long to reign over us; her heir, Charles, was married to Diana, who was was six months pregnant with their first child. If Andrew had been killed in battle, Edward and Anne were still 'spare', and an heir to Charles was due soon. With Diana due to give birth, Andrew's constitutional importance had become almost non-existent.
Whereas, in 2007, the Queen is still long to reign over us but minus 25 years; Charles is nearly 60; and William appears years away from producing an heir. If anything untoward happened to William in the coming few years, Harry would be the last in the direct lineage. Until William produces the goods, Harry should be protected by the British state, not ordered to serve it, and its politicians, in its most dangerous arenas of conflict. The Army would be failing in its duty to protect the monarchy if it allowed Harry to serve on the front-line. Andrew was expendable, then; Harry isn't, yet.