Ideally, I'd like to be able to get an object that has the Express interface, the Caching functionality, and the SOAPProxy implementation, but if they're all just simple subclasses of Net::LDAP, it's awkward to assemble such a beast. (Cf. "diamond pattern".) Perhaps you could accomplish it using mixin classes, but still, ick.

While I agree that is is "ick" in Perl (and Java, and many other languages) and decorators are an excellent solution, this is more a language issue than an issue with multiple inheritance in general. In Eiffel, for example, it's very easy since you have a lot of explicit control over how multiple inheritance occurs.