Unfortunately, yes, after one of my sites was hacked - although the spurious links didn't go to legitimate pages. Are you using Google Webmaster Tools, and if so, is it giving you a warning that your site might have been compromised?
In my case, an additional directory had been added to the site, containing a single file, and the .htaccess file had been edited. All my own files were untouched. I presume you've checked that there are no files on the site that shouldn't be there and your files are clean?