Simple and fairly reliable way of checking if you're running a debug build of your Android app.

DeveloperUtils.java

package org.lucasr;

import java.io.ByteArrayInputStream;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;

import javax.security.auth.x500.X500Principal;

import android.content.Context;
import android.content.pm.PackageManager;
import android.content.pm.Signature;
import android.util.Log;

public class DeveloperUtils {
    private static final String LOGTAG = "DeveloperUtils";

    private static final X500Principal DEBUG_DN =
            new X500Principal("CN=Android Debug,O=Android,C=US");

    private static Boolean sIsDeveloperBuild = null;

    public static void init(Context context) {
        if (sIsDeveloperBuild != null) {
            return;
        }

        try {
            Signature s = context.getPackageManager().getPackageInfo(context.getPackageName(),
                    PackageManager.GET_SIGNATURES).signatures[0];

            CertificateFactory cf = CertificateFactory.getInstance("X.509");
            X509Certificate cert =
                    (X509Certificate) cf.generateCertificate(new ByteArrayInputStream(s.toByteArray()));

            sIsDeveloperBuild = cert.getSubjectX500Principal().equals(DEBUG_DN);

            if (sIsDeveloperBuild) {
                Log.d(LOGTAG, "Is this a developer build? " + sIsDeveloperBuild);
            }
        } catch (Exception e) {
            sIsDeveloperBuild = false;
        }
    }

    public static boolean isDeveloperBuild() {
        return sIsDeveloperBuild;
    }
}