The "express" does not refer to speed, rather to the fact you have the same seat for a fairly long trip through the Alps, traversing them north to south or south to north from Switzerland to Italy. Two lines on this Bernina express route are a designated World Heritage Site.
Wikipedia's Bernina Express page: http://en.wikipedia.org/wiki/Bernina_Express
Summer 2010 Eurail pass Instructions from the Rhätische Bahn, which runs the Bernina Express and other train lines in Switzerland:
Can purchase tickets and reservations for Bernina Express and Bus at http://www.rhb.ch/reservation .
You will be given a "dossier number". With the dossier number you can pick up the travel documents at any train station in Switzerland.
Note: If you do not pick up the tickets/ reservations your total fee will be charged.
General terms of contract are onine here a the Rhätische Bahn website www.rhb.ch/GTC
The Bus from Tirano to Lugano is included in the Eurail pass but you must make a reservation in advance.
You can make reservation for Bus and train in advance without holding the Eurail pass.
One can change the reservation dates (not clear if there is a fee for this or not). Rhätische Bahn said the most important thing is always to inform them of the travel plans and changes to avoid problems.
Rhätische Bahn: http://www.rhb.ch
International Travelers: http://www.swisstravelsystem.
100 years of the Bernina Line www.mybernina.ch
Please note: Eurail Pass is a sponsor of our great European Train Adventure.