Is there a way to use either Redcarpet or Bluecloth such that when it interpolates the markdown it won't make any headers?

For example:

#header 1

yields:

header 1

header 1 (preferred)

And:

##header 2

yields:

header 2

header 2 (preferred)

Well, you can escape characters in Markdown:

# header 1
\# header 1

## header 2
\## header 2

...gives:

header 1

# header 1

header 2

## header 2

If you don't want to have to do this, or you're parsing other people's Markdown and don't have a choice, I would recommend pre-processing the incoming Markdown to do the above for you:

def pound_filter text
  text.gsub /^#/, '\#'
end

Using Redcarpet you can verify that it works:

text = <<-END
  # Hello
  ## World
END

Markdown.new(text.to_html)
# =>  <h1>Hello</h1>
#
#     <h2>World</h2>

Markdown.new(pound_filter text).to_html
# =>  <p># Hello
#     ## World</p>

Of course since a line break in HTML doesn't actually render as such--it will appear as one line:

# Hello ## World"

...you might want to augment that:

def pound_filter text
  text.gsub( /((\A^)|([^\A]^))#/ ) {|match| "\n" == match[0] ? "\n\n\\#" : '\#' }
end

pound_filter text
# =>  \# Hello
#
#     \## World

Markdown.new(pound_filter text).to_html
# =>  <p>\# Hello</p>
#
#     <p>\## World</p>

This last would appear as:

# Hello

## World

Unfortunately you eventually get into weird territory like this, where a heading is inside a quote:

> ## Heading

...but I leave that as an exercise to the reader.