With the following snippet

\setuppapersize[A6][A4] \setuparranging[2*4, doublesided]
\starttext
\dorecurse{8}{
  \input tufte
  \page}
\stoptext

and todays beta using the xp interface with

context --interface=xp

I got the surprising attached result with the arrange pages thrown
onto the sheet with a seemingly random rotation. Also, in a more
complex example with a toc, no toc is made, as if using texexec and
forgetting the --arrange switch. However, adding the --arrange switch
here has an entirely different consequence: only one of the arranged
pages is placed on each sheet, so in effect there is no longer any
arranging. I assume these are not intended behaviours, but would be
happy to be informed I made an error in usage.

Regards, Johan

-- 
Johan Sandblom, MD PhD
m +46735521477  Sweden
"What is wanted is not the will to believe, but the
will to find out, which is the exact opposite"
- Bertrand Russell