I was speaking to Ryan 'Icculus' Gordon recently. I recommended at one point that he relicense one of his programs under the MIT license . He then highlighted a problem with it that I hadn't noticed for a long time.
MIT license {l Wrote}:[...] The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. [...]
Emphasis added on "substantial portions". There is no clarification as to what this is. Does it apply if you just cut and paste some code? Maybe copy parts of a library over but rework them somehow? I'd say dynamic linking is pretty substantial, but really, who defines what is substantial and what isn't?
This is why Ryan uses the zlib license for all of his software. If you don't think zlib's license is permissive enough though, I would definitely suggest the ISC license as an alternative to the MIT license. It offers exactly the same terms in a less verbose manner without the legal uncertainty attached to the MIT license (I quote from the ISC license: "appear in all copies").
The legal uncertainty around the MIT license could cause the license to become void, I believe (unclear on this, but I think that has happened a few times). There are some very large MIT-licensed projects out there like Ruby on Rails and it could prove dangerous. The license does not make it clear what 'substantial' means, and I'd take a clarified license over a weak one like that.