The current plan is to start Belen to Bernalillo in the next 60-90 days. In 2008 the plan is to extend service to Santa Fe. I predict that will not occur for the following reasons.
As you can see from the map, I-25 is the shortest route from Albuquerque (just off the map at lower left) to Santa Fe. At a location called La Bajada, the RR passes under I-25 and turns southeast then northeast and track speed decreases to between 50-60 mph, IIRC. It connects with the Santa Fe Southern spur at Lamy in the NE corner of the map (beneath the highway "84" symbol. The speed limit on the spur to downtown Santa Fe is 15 mph. No one is going to ride a train from ABQ to SF taking this circuitous route that will last for hours (instead of 50-55 minutes by car).
An alternative talked about is to build a new line that essentially follows I-25 to Santa Fe, but the problem is the very steep La Bajada hill that slows down even fast passenger cars because of its steepness. Then there is the further problem of getting a right-of-way through the now heavily subdivided land south of the city. Can you spell NIMBY? The only practical way that I see to overcome this is to build a station at the I-25 crossing at the foot of La Bajada hill and transfer the passengers to shuttle busses for the last 20 miles to the "city different". Of course if you are going to do that, why have a railroad at all when you can have an express bus travel the entire distance at 75 mph (legal limit) in less than an hour??