>> On the other hand, it would be convenient if we could quickly upgrade
>> to the latest ConTeXt on a Mac.
>> ctxtools --update
>> gives me
>> unable to fetch cont-tmf.zip
>>     
>
> same here (OSX 10.4.9)
Maybe you are behind a firewall?, we discussed this on the list earlier 
this year. (BTW upgrading will break XeTeX :-( but maybe you don't mind.

Gr,

Jelle