A fundamental disconnect here seems to be steveb's definition of "getting crawled":
To me, "getting crawled" simply means that the site's home page is known and indexed in G, hopefully in the main index, and that it has a well designed internal link structure that allows G and other robots to crawl each and every page on the site, and that Gbot has in fact been to each and every page of the site at least once. Sufficient evidence of "getting crawled" successfully, to me, is that G has every page of the site either in its main index or supplemental index.
So, "getting crawled", in steveb's terms, really means having IBLs from other sites, not "getting crawled" in the traditional SE spider sense. Mat C's comments that getting quality IBLs is one way to get a URL out of supplementals, but this is still a circular argument. If you, as webmaster/developer for many sites, have the ability to give your own managed site's IBLs from other sites you own and/or manage, that's dandy for you. You have found a way to successfully "game the system", because these links, while perhaps not "purchased", are still not the "natural" links that G is supposedly trying to encourage and reward. And small single-site site webmasters like myself, who do not have the ability to add these unnatural links from many sites, do not have the same advantage. That means we have to buy them or go to extreme efforts to try to convince other webmasters to link to our PR0 internal pages, and why should they? That is the unfairness of this new supplemental scheme.
Finally, G's recent focus on canonicaliazation should mean that simply adding new 301 redirects should not help a target URL, since G will now index that URL only once, in its canonical form, and never under the URL that contains a proper 301 redirect. There may be some "leftovers" from previous times, but if you see the same URL in the main index twice, in any form, then G is not in fact doing what Matt C said they were supposed to be doing with Big Daddy and other recent algo changes in 2006.
If anyone wants to see evidence of this "new supplemental effect", PM me and I will provide a couple of specific examples.