Over at Crooked Timber, Daniel Davies takes up the question of what war crimes Hezbollah and Israel might be committing in the current war. For Hezbollah's part, firing rockets into Israeli cities seems to be the chief war crime (unless, of course, one believes Hassan Nasrallah that they're being aimed at military targets); rightly or wrongly, it's unlikely that the group would ever be indicted for crimes of "aggression," and it's not always clear whether Hezbollah fighters are committing the crime of "sheltering" by mixing among civilians. In some places, they appear to be doing so, in others, it's more ambiguous.
On that point, I'd note Mitch Prothrero's report in Salon arguing that it is extremely unlikely that Hezbollah fighters are actually mixing in with civilians in Lebanonpartly because they fear they'll be betrayed by the general populationin which case Israel is certainly committing a war crime by bombing civilian neighborhoods without any clear military targets. Moreover, Human Rights Watch has condemned Israel's use of cluster bombs, which are "unacceptably inaccurate," in civilian areas. At this point, the legal questions hare are probably moot, since it seems that neither side will ever see a day in court, but it's still worth pointing out.
Update: See also the New York Times yesterday, in which Israel's Justice Minister, Haim Ramon, announced that "all those now in south Lebanon are terrorists who are in some way related to Hezbollah." "In some way related"? Hezbollah, of course, is more than a militia, and employs some 250,000 Lebanese in various capacities, including schools, grocery stores, and orphanages.
More: More background from Human Rights Watch.