We visit Palm Desert 1-2 times a year and it's a great place, but there isn't much local wakeboarding. There is a private lake that offered lessons and was working on a cable park but they've been shutdown for over a year now, without any status updates.
http://www.desertwakeinfo.com/
There is also a private ski community called Shadow Lake Estates (or something similar) but I doubt you'll get a ride there.
We'll be down there the end of May, but I don't plan on doing anything but laying by the pool and drinking