what's the earliest wordpress action in which the publish which will eventually become proven could be detected dependably ? (either by utilizing global $publish or discovering the wordpress_query object or any other way)

eg. my wordpress plugin must identify an incoming request from another wordpress plugin on the different site, right now it inspections for any $_Publish var as soon as possible by utilizing add_action('plugins_loaded' and also the callback function uses $post = get_page_by_path($_SERVER['REQUEST_URI'],'','post') to obtain the $publish object after which uses the publish data to obtain every other information that's accustomed to process the response which will get delivered back before any headers or any other standard Wordpress processing happens using the aim of reducing the burden around the blog finding the request.

it is possible to better way?, I understand there is not an early on way because 'plugins_loaded' action will get known as immediately after the , well, plug ins get loaded but it is possible to more reliable way than using get_page_by_path ?

I’d try the filter 'the_posts'. You discover it in wp-includes/query.php function get_posts(). It passes the found posts like a array by reference, so technology-not only as an action.

This is a wordpress plugin I personally use to examine hooks:

<?php
/*
Plugin Name: Hook Check
Description: Inspects a hook and prints its information to the footer.
Version:     1.0
Required:    3.1
Author:      Thomas Scholz
Author URI:  http://toscho.de
License:     GPL
*/
! defined( 'ABSPATH' ) and exit;

$GLOBALS['hook_checks'] = apply_filters(
    'hook_check_filter'
,   array ( 'the_posts' )
);

foreach ( $GLOBALS['hook_checks'] as $hc_hook )
{
    add_action( $hc_hook, array( 'Hook_Check', 'catch_info' ) );
}
add_action( 'wp_footer', array( 'Hook_Check', 'print_info' ) );

class Hook_Check
{
    static $info = array ();

    public static function catch_info()
    {
        $args = func_get_args();
        self::$info[ current_filter() ] = print_r( $args, TRUE );
        return $args[0];
    }

    public static function print_info()
    {
        if ( empty ( self::$info ) )
        {
            return;
        }

        print '<pre>';
        foreach ( self::$info as $filter => $catched )
        {
            print "<b>$filter</b>\n" . htmlspecialchars( $catched );
        }
        print '</pre>';
    }
}

Reduced sample Output:

Array
(
    [0] => Array
        (
            [0] => stdClass Object
                (
                    [ID] => 112
                    [post_content] => The entire content …
                    [post_title] => An awesome title
                    [post_excerpt] => 
                    [post_status] => publish
                )
        )
)

This will provide you with all important information as soon as possible.

Oh, and that i aspire to help you on http://wordpress.stackexchange.com/ with your questions. :)