>>21
Yea.
>>22
What? I'm using SBCL, and it works fine on most platforms. CCL works very well too, CLisp works mostly fine as well. I don't know what you mean by usability, but these implementations comply with the standard pretty well(some better than others). Not free? Public domain isn't free enough for you? LLGPL isn't free enough for you? Unless you mean the perverted kind of "freedom" that GPL provides (that would be crazy for a Lisp implementation, as it would require everyone to publish source for any applications used in an implementation if you distribute binaries).
What exactly does 'usable quality' mean to you? I find developing in Emacs+SLIME very comfortable and pleasant: it's truly interactive development, much better than how it feels when developing in other languages. Commercial Lisps are also in very good condition, but you didn't ask about them, so I won't talk about them. As for developing on the Genera, some people are still doing it, and I don't see a problem with it as long as you indend to write portable CL code. Sources to the Genera are available, and you can do as you wish, and its presentations are "true" presentations (not like the SLIME emulation of them, which is enough for development purposes). If you want a moderm LispOS-like dev environment, you might also want to look at McCLIM, but I don't have much experience with it.