Working on typescripts for Y&Y's LucidaBright (which are type1 fonts)  
for MKIV (hoping to maintain compatibilty with MKII), the following  
code produces all math in bold, even the first x+y.
   \usetypescript[luc]\setupbodyfont[luci]\starttext $x+y$ -- $\bfmath  
x+y$ \stoptext

I studied the new manual chapter on typescripts as well as have worked  
in analogy with existent typescripts in the current ConTeXt base. I  
certainly am missing an important clue here.

The relevant portions of the typescript are:

\starttypescriptcollection[luci]

\starttypescript [luci]
   \definetypeface [luci][mm][math][lucibr][default]
   \definetypeface [luci][mm][bfmath][lucibr][default] % removal  
prints nonbold math only
\stoptypescript
...
% typescripts for text in serif, sans etc. omitted but contain:
   \definefontsynonym [LucidaBright][lbr.tfm][encoding=\typescriptthree]
   \definefontsynonym [LucidaBright-Demi][lbd.tfm][encoding= 
\typescriptthree]
...
\starttypescript [math] [lucibr] [name]
   \usemathcollection [lucibr]
   \definefontsynonym [MathRoman][LucidaBright] ... etc.
   \definebodyfont [default] [mm] [mr=MathRoman mo 1, ex=MathExtension  
mo 1, ... etc.]
   .. math font tfm definitions
\stoptypescript
\starttypescript [bfmath] [lucibr] [name]
   \usemathcollection [lucibr]
   \definefontsynonym [MathRomanBold] [LucidaBright-Demi] ... etc.
   \definebodyfont [default] [mm] [mrbf=MathRomanBold mo 1,  
exbf=MathExtensionBold mo 1, ... etc.]
   .. bold font tfm definitions
\stoptypescript

\stoptypescriptcollection

Hans van der Meer