For those of us who aren't priviledged enough to hold dual citizenship with a European nation (or any other country besides US/Canada), Amtrak is now selling the USA Railpasses to all. Previously, these less-expensive passes were only available to international visitors and US/Canadian citizens whose permanent residence was outside of the US/Canada. The copy on Amtrak's website is not yet updated, but you can purchase the passes through 1-800-USA-RAIL or at an Amtrak station.
National (Map)
15 Days
Peak $499
Off-Peak $389
30 Days
Peak $599
Off-Peak $469
Eastern (Map)
15 Days
Peak $369
Off-Peak $329
30 Days
Peak $459
Off-Peak $359
Western (Map)
15 Days
Peak $369
Off-Peak $329
30 Days
Peak $459
Off-Peak $359