Sirius Satellite Radio [SIRI] said today that it has surpassed the 700,000-subscriber mark and had its best month ever for new subscribers in September, with the addition of 69,000 subs. The company attributed the growth last month to a variety of factors, including traction in the retail market and new programming additions – NFL, NCAA Div. I-A college football coverage, Eminem’s “Shade 45,” Maxim radio and the announcement that New York shock jock Howard Stern will be joining the Sirius programming lineup in January 2006. Sirius said it is on target to hit the 1-million-subscriber mark by the end of the year.