Just like in the emoticon tag. It would allow me to to specify how many columns of entries to show.

The problem with this is that the emoticon code is wrapped in tables.  Even in the php code to some extent, from what I saw. 

The weblog stuff is *not* wrapped in tables, unless you add it.  Especially not in the php code (unlike the smilies) - and so having this feature would be confusing and difficult to implement and not confuse a lot of people.

MT has a plugin called MT Grid which forced iteration of entries over a table.  You might put in a plugin request for someone to try to mimic that here.  I can see that being useful for photoblogs etc. =)