I just now wrote:
FWIW, I also think we should go a little easier on banning anonymous users than has been done lately. Certainly if somebody vandalizes a bunch of pages they should be banned, but I don't think it's necessary to ban an IP that's had two minor vandalism edits, especially if they're the sort that might be unintentional (just adding "hi" or something, often done by newbies to test if you really can just edit any page, as advertised). We can end up discouraging potential contributors with stuff like that, and the downside of having to revert a few more edits isn't really a big one (it's pretty easy to revert, after all). I personally tend only to ban users who insist on vandalizing the same page, or have vandalized somewhere more in the range of 8-10 pages; the rest usually either turn into good users or give up and leave before banning them is necessary.
I forgot to add--I also think that when anonymous users of that sort *are* banned, the ban messages should make some attempt to be at least tersely polite and directed towards the banee rather than towards the sysops reading the ban log. For example, "yawn, another vandal" isn't as good as "please do not vandalize articles" or something of that sort.
Also, perhaps the ban message should tell them it's only a 24-hr ban? Something like "Your ban will automatically expire in 24 hours, after which you may resume editing Wikipedia in accordance with our policies. If you persist in vandalism or other violations of our policy, however, you will be permanently banned."
-Mark