how does maintaining a blockade of lebanon serve israeli interests? putting aside whether israel was right or wrong to do it in the first place, i don't see how keeping lebanese ports and airports closed serves any purpose for the israelis.
in international law a blockade is considered to be an act of war, just like a military attack or invasion. in other words, if one country blockades another, then the blockaded country is justified under international law to attack the blockader. in this case, israel claims that it has no beef with the lebanese government, only hezbollah. that's why israel insisted upon the lebanese army come into southern lebanon along israel's southern border. yet its blockade is directed at all of lebanon. the action directly contradicts israel's official stance. it not only imposes more hardship on the lebanese people, it also it means that lebanese troops now lining the israeli-lebanese border would be justified under international law if they started firing south.
don't get me wrong, i think there is zero chance that lebanon will do that. they have no incentive to, and unlike israel the lebanese government seems to be acting in a way that at least arguably serves their national interests. but it means that israel, once again, has taken whatever justification it might have once had for its actions and flushed it down the toilet.
but most importantly putting international law aside, the blockade is simply stupid policy. lebanon, like many small countries, relies on imports. because the israeli-lebanese border is heavily militarized and closed there's only three ways to get goods into lebanon: by sea, by air and through one of the border crossings with syria. an air and naval blockade closes off the first two options, leaving only the syrian border. yet israel claims it is maintaining the blockade to stop weapons shipments from syria.
the blockade forces lebanon to get all of its shipments through syria. that makes lebanon more dependent on syria and increases the chances that weapons will be smuggled into lebanon that supplies moving across the border.
the only reason i can come up with for the continuation of the israeli blockade is simple testosterone poisoning. the olmert government went into lebanon to prove that they had cajones. the policy was a colossal failure, accomplishing none of its stated goals. almost two-thirds of the israeli public wants olmert to resign over the bungled operation. olmert doesn't want to add the blockade to the pile of embarrassments, so he's keeping it in place until the international forces arrive (if ever).
at least that's the best theory i can come up with. maybe someone out there has a better one.