One of the challenges working as a programmer is keeping up with new technologies. Although many appear promising if you decide to spend the time to learn something new it needs to pay off in the long run.
There are two sites I primarily use to help decide, I consider both to be good leading indicators of the future success of a language/framework/library/etc.
All technologies will eventually go out of date, the challenge is picking ones that will hang around for a while.
Hillel Coren 