Index: wp-includes/formatting.php
===================================================================
--- wp-includes/formatting.php	(revision 4279)
+++ wp-includes/formatting.php	(working copy)
@@ -613,7 +613,7 @@
 		for ($i = 0; $i < $stop; $i++) {
 			$content = $textarr[$i];
 			if ((strlen($content) > 0) && ('<' != $content{0})) { // If it's not a tag
-				$content = str_replace($wp_smiliessearch, $wp_smiliesreplace, $content);
+				$content = preg_replace($wp_smiliessearch, $wp_smiliesreplace, $content);
 			}
 			$output .= $content;
 		}
Index: wp-includes/vars.php
===================================================================
--- wp-includes/vars.php	(revision 4279)
+++ wp-includes/vars.php	(working copy)
@@ -43,7 +43,7 @@
 	':arrow:'	=> 'icon_arrow.gif',
 	':shock:'	=> 'icon_eek.gif',
 	':smile:'	=> 'icon_smile.gif',
-	' :???:'	=> 'icon_confused.gif',
+	':???:'	=> 'icon_confused.gif',
 	':cool:'	=> 'icon_cool.gif',
 	':evil:'	=> 'icon_evil.gif',
 	':grin:'	=> 'icon_biggrin.gif',
@@ -57,28 +57,28 @@
 	':lol:'		=> 'icon_lol.gif',
 	':mad:'		=> 'icon_mad.gif',
 	':sad:'		=> 'icon_sad.gif',
-	' 8-)'		=> 'icon_cool.gif',
-	' 8-O'		=> 'icon_eek.gif',
-	' :-('		=> 'icon_sad.gif',
-	' :-)'		=> 'icon_smile.gif',
-	' :-?'		=> 'icon_confused.gif',
-	' :-D'		=> 'icon_biggrin.gif',
-	' :-P'		=> 'icon_razz.gif',
-	' :-o'		=> 'icon_surprised.gif',
-	' :-x'		=> 'icon_mad.gif',
-	' :-|'		=> 'icon_neutral.gif',
-	' ;-)'		=> 'icon_wink.gif',
-	' 8)'		=> 'icon_cool.gif',
-	' 8O'		=> 'icon_eek.gif',
-	' :('		=> 'icon_sad.gif',
-	' :)'		=> 'icon_smile.gif',
-	' :?'		=> 'icon_confused.gif',
-	' :D'		=> 'icon_biggrin.gif',
-	' :P'		=> 'icon_razz.gif',
-	' :o'		=> 'icon_surprised.gif',
-	' :x'		=> 'icon_mad.gif',
-	' :|'		=> 'icon_neutral.gif',
-	' ;)'		=> 'icon_wink.gif',
+	'8-)'		=> 'icon_cool.gif',
+	'8-O'		=> 'icon_eek.gif',
+	':-('		=> 'icon_sad.gif',
+	':-)'		=> 'icon_smile.gif',
+	':-?'		=> 'icon_confused.gif',
+	':-D'		=> 'icon_biggrin.gif',
+	':-P'		=> 'icon_razz.gif',
+	':-o'		=> 'icon_surprised.gif',
+	':-x'		=> 'icon_mad.gif',
+	':-|'		=> 'icon_neutral.gif',
+	';-)'		=> 'icon_wink.gif',
+	'8)'		=> 'icon_cool.gif',
+	'8O'		=> 'icon_eek.gif',
+	':('		=> 'icon_sad.gif',
+	':)'		=> 'icon_smile.gif',
+	':?'		=> 'icon_confused.gif',
+	':D'		=> 'icon_biggrin.gif',
+	':P'		=> 'icon_razz.gif',
+	':o'		=> 'icon_surprised.gif',
+	':x'		=> 'icon_mad.gif',
+	':|'		=> 'icon_neutral.gif',
+	';)'		=> 'icon_wink.gif',
 	':!:'		=> 'icon_exclaim.gif',
 	':?:'		=> 'icon_question.gif',
 	);
@@ -87,7 +87,7 @@
 
 // generates smilies' search & replace arrays
 foreach($wpsmiliestrans as $smiley => $img) {
-	$wp_smiliessearch[] = $smiley;
+	$wp_smiliessearch[] = '/(\s|^)?'.preg_quote($smiley, '/').'(\b|\s)/';
 	$smiley_masked = htmlspecialchars( trim($smiley) , ENT_QUOTES);
 	$wp_smiliesreplace[] = " <img src='" . get_option('siteurl') . "/wp-includes/images/smilies/$img' alt='$smiley_masked' class='wp-smiley' /> ";
 }