In late June 2005, Google announced that it was launching in beta mode it's new XML Sitemap protocol which is a completely new and different approach to the website submission process.
By creating an XML Sitemap to Google's specifications and adding it to your website, you are effectively providing Google with the means to crawl and index your complete site very quickly which should, in the long term, ensure that all your web pages eventually appear in Google's listings.
Although not yet a replacement for the conventional submission process, if it proves successful it is likely to be a standard that will be adopted by all the major search engines in the future, given that the XML Sitemap can be read and accessed by all other search engines as well.
Of course to be successful, your website and individual pages must still be correctly optimised for the search engines in the first instance, and this is something which cannot be overlooked and is essential.