packages/SystemUI/res/anim/recent_app_enter.xml

<?xml version="1.0" encoding="utf-8"?>
<!--
/*
** Copyright 2009, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License"); 
** you may not use this file except in compliance with the License. 
** You may obtain a copy of the License at 
**
**     http://www.apache.org/licenses/LICENSE-2.0 
**
** Unless required by applicable law or agreed to in writing, software 
** distributed under the License is distributed on an "AS IS" BASIS, 
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
** See the License for the specific language governing permissions and 
** limitations under the License.
*/
-->

<!-- Special window zoom animation: this is the element that enters the screen,
     it starts at 200% and scales down.  Goes with zoom_exit.xml. -->
<set xmlns:android="http://schemas.android.com/apk/res/android"
        android:interpolator="@android:anim/decelerate_interpolator">
    <scale android:fromXScale="0.25" android:toXScale="1.0"
           android:fromYScale="0.25" android:toYScale="1.0"
           android:pivotX="0%p" android:pivotY="0%p"
           android:duration="500" />
    <alpha android:fromAlpha="0.0" android:toAlpha="1.0"
            android:duration="500"/>
</set>