This seems kind of contrived, since you can already use a lisp to target the JVM, CLR and the browser. But I guess since the author thinks lisp adoption (??) is a political imperative, maybe I'm just missing the point.
I'm somewhat confused why you think this is contrived. Clojure isn't a Common Lisp implementation and the ecosystem around each is very different, Heroku is a nice platform for cloud hosting and there are very few (possibly no) good options for deploying CL-based web apps other than on machines you run yourself. Since some people like using Common Lisp (ITA Software being the classic example, but they're not the only ones) simplifying the process seems helpful. Would it help if I rephrased your objection as pointing out that there's no reason to work on GNU Classpath since C#/Mono exists?
SBCL is still the best open source CL(on linux at least), but ABCL is definitely getting better and better, its worth a look at the very least. I've been meaning to try it out for a while now, it looks very promising. I would also like to know if anybody has done anything interesting with it.
Arguably only Lisp Machines hold that distinction. The other common targets are C, LLVM,Arm and x86. I don't see how they can be said to be designed any more specifically for lisp. At least the LLVM and CLR have TCO.
This is very true. And any language to language transfomation is going to have some impedance mismatch. Nonetheless, it does not follow that since JVM was built specifically for Java, the impedance mismatch of Lisp -> JVM would result in a less expressive lisp than Lisp -> C or Lisp to x86. There are many variants of lisps and clojure is not specially disadvantaged due to targeting the JVM.
x86 is aimed at Pascal and other stack-based languages.
The processor had some new instructions (not present in the 8080 and 8085) to better support stack based high level programming languages such as Pascal and PL/M; some of the more useful ones were push mem-op, and ret size, supporting the "pascal calling convention" directly.http://en.wikipedia.org/wiki/Intel_8086