Now that this day has arrived, we can see that it wasn't as deserving of all the pomp and circumstance to which we were planning for it to be attributed. Seems that there are a considerable amount of deficiencies and intentional short comings to the language. Normally this wouldn't be seen as anything out of the ordinary for a 'new' language, and would be generally a non-issue.
The problem is that this is the year 2008 and people have come to expect more from their languages. Ignoring established standards along with ignoring the need for designing to meet the needs of developers globally all the while using the cop-out of it being purely for exploratory programming is just bad form.
The world doesn't need another Lisp, the original is wonderful just as it is, that's part of its beauty. I don't see anything in Arc that couldn't be done as functions and/or macros in Lisp that required the entire 'creation' of a new language. The way I see it is this; for prototyping as well as production usage we already have several languages that excel in those domains, specifically Lisp and Python.
Generally the idea of rewriting existing languages with little difference from their predecessor(s) is a waste of time and effort which could've been better spent elsewhere. There are exceptions to this scenario such as that of Ruby. It is a language that in the past I used to dislike because of certain key flexibilities much akin to the reasons for spaghetti perl, but it successfully fixes many of perl's wrongs, and corrects some of Pythons short comings as well. It serves serves enough of a purpose as that of supplanting perl with a better thought out design, and thanks to Rails, its future looks solid.
Arc on the other hand is like a still born fetus. Much was expected and there was potential to be just like its parent(s), but death was announced during a delayed delivery and upon further examination, it was discovered that it wasn't a proper offspring, but a clone in fetal form. My advice to Paul and Robert is the following: recall the release, and make it truly something worthy of release, with proper compatibility and compliance with modern norms. Make it usable to others as opposed to just a few tinkerers interested more in lisp and scheme basics.
An on a more pleasant note to Paul; Please keep on writing your essays and providing your viewpoints as they are appreciated, I just wish that your judgement call in the case of 'Arc' was as well thought out as your writings have proven to be over time.