http://altern.org/mn/ruby/ruby.vim latest updates:

 * Block support was buggy. Should now be fixed, at the expense of 
   ignoring "do" when redundant (e.g after a "while"); option to
   disable this feature by setting "ruby_no_expensive";
 * "Here-doc" forms, thanks to Reimer Behrends;
 * ASCII codes; backslash notation in strings;
 * All delimiters allowed in generalized string/regexp forms (except 
   newline).

I think now it is already fairly complete.

Reimer Behrends wrote:
> > > Main problems remaining:
> > > Reliably parsing "here documents".
> > Mine support only EOF (like perl.vim). Other labels can be added, but
> > i doubt we can find a generalized way.
> 
> I went for supporting a couple of standard ones, and otherwise just to
> terminate the pattern whenever I encountered a line made up of just
> capital letters (with initial whitespace allowed for the <<-EOF variant).
> 
> This is probably less of a problem than just letting the highlighting
> mechanism run amok over arbitrary text.
> 
> By the way, I believe your syntax file doesn't yet allow <<-EOF,
> <<'EOF', and <<"EOF"?
>
I didn't know this form well, indeed. Only now i undestand that 
initial whitespace is allowed only for the <<-EOF variant.

Think your idea is reasonably good, so i've merged it in my file.
Thank you. :)

> > > Handling %[qQrxw] constructs that span multiple lines (same problem).
> > Mine does, but not for all delimiters (again, like perl.vim).
> 
> I've wondered if it is feasible (i.e. doesn't slow down highlighting
> significantly) to have these patterns automatically pregenerated by a
> quick script.
> 
I've given it a try and it doesn't seem to be too slow.
(The quick script is at http//altern.org/mn/ruby/vimregions.rb , just
in case.)

Matz in the manual says newline is a valid delimiter, but Vim doesn't
support newline match, yet.

> > Other problems:
> >   * characters, like ?a or ?\M-a: where are they documented?
> 
> Check the irb package, ruby-lex.rb has a read_escape routine that
> parses all of them (well, kindof). [...]
> 
Done, thank you. They're in the manual, too, at a better look.

Ciao.

-- Mirko Nasato