Index: wp-admin/press-this.php
===================================================================
--- wp-admin/press-this.php	(revision 25039)
+++ wp-admin/press-this.php	(working copy)
@@ -602,12 +602,11 @@
 			$content .= $selection;
 
 		if ( $url ) {
-			$content .= '<p>';
+			$via = $selection ? __('via ' ) : '';
 
-			if ( $selection )
-				$content .= __('via ');
+			$source = sprintf( '<p>%1$s <a href="%2$s">%3$s</a></p>', esc_html( $via ), esc_url( $url ), esc_html( $title ) );
 
-			$content .= sprintf( "<a href='%s'>%s</a>.</p>", esc_url( $url ), esc_html( $title ) );
+			$content .= apply_filters( 'press_this_source', $source, $url, $title );
 		}
 
 		remove_action( 'media_buttons', 'media_buttons' );