followbutton1.js

// Original code from David Walsh
jQuery(document).ready(function() {
	/* fetch elements */
	jQuery('form.follow-form').each(function() {
		/* stop form event */
		jQuery(this).bind('submit',function(e) {
			/* stop event */
			e.preventDefault();
			/* "on request" */
			jQuery(this).find('i').addClass('active');
			/* "save" button */
			var button = jQuery(this).find('button');
			/* send ajax request */
			jQuery.post('twitter-follow.php',{
				followID: jQuery(this).find('input').val()
			},function() {
				/* hide button, create element */
				button.css('display','none').after('<span class="following"><span></span>Following!</span>');
			});
			
		});
	});
});

followbutton2.js

// Idiomatic jQuery by Doug Neiner
jQuery(function ($) {
	/* fetch elements and stop form event */
	$("form.follow-form").submit(function (e) {
		/* stop event */
		e.preventDefault();
		/* "on request" */
		$(this).find('i').addClass('active');
		/* send ajax request */
		$.post('twitter-follow.php', {
			followID: $(this).find('input').val()
		}, function () {
			/* find and hide button, create element */
			$(e.currentTarget)
			  .find('button').hide()
			  .after('<span class="following"><span></span>Following!</span>');
		});
	});
});

followbutton3.js

// How I would actually write it (using live or delegate depending on context)
jQuery(function ($) {
	/* fetch elements and stop form event */
	$("form.follow-form").live("submit", function (e) {
	    // Everything else the same
	});
});