The WiFi information can be accessed by registering your application as a wifi intent receiver as shown below:
mIntent_Receiver = new Intent_Receiver();
mIntentFilter = new IntentFilter();
See http://developer.android.com/reference/android/net/wifi/WifiManager.html for the values included as extras in the received intent.
The attached sample demonstrates the use of Android WiFi APIs for enabling, disabling and determining the status of WiFi.