Here is what I have been able to find.
The Riverside County Transportation Commission passed a resolution in October 2013 supporting daily intercity rail service from Los Angeles to the Coachella Valley.
Here is the Coachella Valley Intercity Rail Corridor Planning Study from 2013 by Caltrans.
Here is the current RCTC Fact Sheet on the project.
In the maeantime, I am wondering how that Sunline Transit Commuter Bus 220 service is fairing. Also, I have friends who occasionally take Amtrak from Los Angeles to Fullerton and then catch the Amtrak bus to the Coachella Valley and then back the same way when returning. Those Amtrak buses are nice and have WiFi..
Two big questions remain:
(1) Should passenger rail service between Los Angeles and the Coachella Valley be a Metrolink operation or an Amtrak operation? If there are sufficient people who would commute daily to work from the Coachella Valley and Riverside or even Los Angeles, the Metrolink makes sense. If this is more resort and holiday travel, then perhaps Amtrak is the more suitable carrier. Either way, we all want to Palm Springs and Coachella Valley having daily stops in the morning and evening. And if that happens will Palm Springs upgrade its station with amenity or two?
(2) Competition with Freight Rail for use of those tracks. Right now the freight rail carriers do not want to share the tracks for daily passenger rail service. Approximately 40% of America's incoming goods go through the Ports of Los Angeles and Long Beach, so you can see why. Is the answer for the federal government to make them share the tracks with passenger rail through regulation or is it to find the money to build more tracks or both?
That is where we are at and as soon as I know more I will let you know.