This is pretty standard practice really... many e-mails will have a "tracking pixel" or similar. Facebook has this in their e-mails too: https://www.facebook.com/email_open_log_pic.php?mid= =blah" style="border:0;width:1px;height:1px;" />
Yes, but about 100% of email clients now don't load images -- whether webbugs or actual content -- because of that. This BGSOUND tactic certainly isn't standard practice, despite being an extension of a prior technique, extended specifically to get around the existing filter.
There was a time when the iOS email client (and Apple Mail too) would actually load content from the html audio and video tags, even when remote images were disabled.