Maps for buses do not load in IE8

[scottsil]

error message from IE8 (*note IE8 runs in the Windows 7 Parallels instance on the media monster):

Webpage error details

User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.1; WOW64; Trident/4.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0)
Timestamp: Sun, 26 Jun 2011 03:18:08 UTC

Message: Object doesn't support this property or method
Line: 18
Char: 7
Code: 0
URI: http://schoolbus.heroku.com/busses