I'll add that the US "refund" is in the form of a voucher for future travel, not cash.

As the above posters have noted, the fare difference needs to be at least $301 to make it worthwhile (and in that case you'd only get $1). If the price falls again you'll be hit with the same $150 x 2 change fee to re-fare again.

There are other gotchas too. In short, they suck.

http://www.usairways.com/awa/content...s/default.aspx

Lower fare guarantee

When a new lower fare becomes available after a ticket has been purchased, customers are entitled to a lower fare guarantee refund within the following guidelines. We will deduct a $150 change fee ($250 for international travel) and apply residual funds in the form of a US voucher. Additional rules and restrictions may apply. Call our Reservations Desk to seek a lower fare guarantee.

* The lower fare is available for the exact itinerary previously purchased.
* No portion of the reservation has been flown.
* Lower fare guarantee refunds are not available for online ticket exchanges. Certain promotional fares may be excluded.