What is the copyright status of SICP? Is it permitted (in letter, and in
spirit) to publish the full text online?

I thought it's not officially permitted, but the page
https://www.neilvandyke.org/sicp-texi/ says:

> MIT Press now distributes the second edition of the book Structure and Interpretation of Computer Programs (SICP) in HTML format. Lytha Ayth converted the book to Texinfo format, so that the book can be viewed in Emacs. [...]
>
> I've made very minor modifications to a version of sicp.texi that was circulating informally at MIT, and distribute my modified version (and a compiled sicp.info of it) via this Web page.

There is also the repository https://github.com/sarabander/sicp-pdf and
its companion blog https://sicpebook.wordpress.com/ which produce a
beautiful PDF, apparently from the same sources.

If this is now a thing that is done "in broad daylight", scheme.org
should definitely join in the fray and publish some of the goodies
produced by these people.

But does this activity have the authors' blessing?