Hosting Issue: Apache serving pages not as utf-8

Was this a problem with Boost 1.03, or is this a new install? You want to save in utf-8 correct?

Is there any way to detect win-1251?

Possible Solutions Today:
http://php.net/utf8-encode before saving file
http://php.net/iconv to convert it
http://php.net/utf8-encode#74905 - Example

Possible Solutions With PHP 6.0:
http://php.net/stream-encoding
http://php.net/file-put-contents with the FILE_TEXT

You can play around with what is written to the cache by implementing this hook
hook_boost_preprocess()

/**
 * Edit document before it is put into the boost cache.
 *
 * This hook is run at right before the page is cached by boost.
 *
 * $GLOBALS['_boost_cache_this'] and $GLOBALS['_boost_router_item'] are useful.
 * set $GLOBALS['_boost_cache_this'] = FALSE if you wish to not cache this page.
 *
 * @param $path
 *   URL path of the document
 * @param $data
 *   String containing the data
 * @param $extension
 *   file extension type. Use to detect what type of document your operating on.
 * @return
 *   $data string containing the document
 */
function hook_boost_preprocess($path, $data, $extension) {
  return $data;
}

mytheme_boost_preprocess() should do the trick

PHP6 allows for saving files in a specific charset. Boost uses file_put_contents() to save the cached file.

What if I make the default so Boost always saves in utf-8. Could you see any issues with that?

http://httpd.apache.org/docs/trunk/mod/core.html#adddefaultcharset

The actual file is not the problem, its your webserver. It's configured to send out win-1251 by default. By turning this off it solves your issue. You could also do this and it would have the same effect.

AddDefaultCharset utf-8 

This is something that I might want to add to the default .htaccess rules, but I'm not 100% certain.

Could you let me know if adding this to your htaccess file fixes the issue?

AddDefaultCharset utf-8 

Code patch for above proposed change

committed