So, just to sum-up:
Nexus S i9023:
-WiFi connects but doesnt work.
-Calls/sms work, but no data
-If flashed Netarchy Kernel, stuck at boot logo.
This is my XP, so mileage may vary.
For everyone with WiFi problem:
1. Try to connect to your network - it will most likely not work.
2. Disconnect and forget the network.
3. Connect again, then it should work.
That's what I did anyway, and it works just fine.
Also, I get decent performance in Cut the Rope and Google Earth, though it's better on GB. Just thought I should say this.
EDIT: Surprisingly enough, 3rd party keyboards works without problems. Only tried SwiftKey, though.