Glock sent notice to all its active Armorers that they will now swap the recoil spring assembly (RSA) on any Gen4 Glock. I had heard before that this would be done on a case by case basis. Apparently Glock has decided that all Gen4 guns that want one should get them.
Personally, I have not had anyone come to me with RSA problems. On the other hand, you can read about them on just about any shooter forum. I've heard they happened mostly with the G17, large frame 9mm. I know shooters with G35s and G19s who told me they don't have any issues.
If you have a Gen4 gun and you want the RSA swapped out, just contact any certified Glock Armorer and they can do it, but they will need to order the part from Glock so don't expect While-You-Wait service. On the other hand, you can take your gun to any GSSF match and have it done immediately by the factory Armorers. I only hope they bring enough new parts to the match.
The notice also says "Agencies or Consumer’s wishing to participate in the exchange program at no charge are urged to call 1-877-745-8523 to order their new RSA," so I assume individuals can contact them if you wish.
I will continue to monitor the situation, as they say, and let you know what I hear.
Update: to learn more about the Gen4 recoil spring issues, take a look over at pistol-training.com. ToddG has been doing a Gen4 G17 endurance test for quite a while and explains it all.