user1302: I have an Arduino GSM Shield mounted on an Arduino Uno. Can I stack this GPS shield above Arduino GSM shield? Will there be any pin configuration problem?
In GSM Shield hardware pin’s configuraton are as below:
0 - Not connected
1 - Not connected
2 - GSM Rx
3 - GSM Tx
7 - Modem reset

If there is any problem, how can it be solved? I would be happy if there are any alternatives for the GPS shield.

Addendum
The schematic of the Arduino GSM shield:

The schematic of the SparkFun GPS shield:


user1155: From the shield description, the TX and RX of the GPS are mapped on pins 2 & 3, like your GSM, so you'll have to change that.
I'm using Adafruit GPS + flash card shield, which is a bit cheaper (and uses pins 7&8).

user316: 
Photo by John Boxall
Which pins do they use?
To determine if two shields are compatible, you have to read the specifications of both shields.
The best source for this information is the data sheets supplied with the shields. However there is also this Shield List
Can you reassign pins?
Some shields provide a means to alter which pins are used for communications. This can take the form of a switch or a jumper - either pull-off or solder-bridge type. (the GPS shield in the question has jumpers).
Where the shields do not support pin-reassignment or provides insufficient flexibility, to work-around incompatibilities you can use an in-between shield designed for the purpose.
here is one example:

You hear it all the time in the Arduino community, “will this shield work with my other shield?.” I think we’ve all been disappointed to find that two of our favorite shields compete for control of a digital pin here or a serial pin there. While there are sometimes some clever workarounds from elegant code modifications to aggressive ‘greenwiring,’ Mayhew Labs may have come up with the simplest solution thus far: The Go-Between Shield.

Are any alternatives for the foo shield
I notice that Arduino.cc now point people to the list referenced above. They used to have their own list.
Product recommendations are off-topic here but, obviously, you can search

1302: <p>I have an Arduino GSM Shield mounted on an Arduino Uno. Can I stack this <a href="https://www.sparkfun.com/products/10709#comment-5366048bce395fa40e8b4567" rel="nofollow noreferrer">GPS shield</a> above Arduino GSM shield? Will there be any pin configuration problem?</p>

<p>In GSM Shield hardware pin’s configuraton are as below:</p>

<pre><code>0 - Not connected
1 - Not connected
2 - GSM Rx
3 - GSM Tx
7 - Modem reset
</code></pre>

<p>If there is any problem, how can it be solved? I would be happy if there are any alternatives for the GPS shield.</p>

<hr>

<h3>Addendum</h3>

<p>The <a href="http://arduino.cc/en/uploads/Main/arduino-gsm-shield-schematic.pdf" rel="nofollow noreferrer">schematic of the Arduino GSM shield</a>:
<img src="https://i.stack.imgur.com/7ttFF.png" alt="schematic of the Arduino GSM shield"></p>

<p>The <a href="https://cdn.sparkfun.com/datasheets/Dev/Arduino/Shields/GPSShield-v16.pdf" rel="nofollow noreferrer">schematic of the SparkFun GPS shield</a>:
<img src="https://i.stack.imgur.com/zZUxI.png" alt="schematic of the SparkFun GPS shield"></p>
 1155: <p>From <a href="https://www.sparkfun.com/products/10710" rel="nofollow">the shield description</a>, the TX and RX of the GPS are mapped on pins 2 &amp; 3, like your GSM, so you'll have to change that.</p>

<p>I'm using Adafruit GPS + flash card shield, which is a bit cheaper (and uses pins 7&amp;8).</p>
 316: <p><img src="https://i.stack.imgur.com/I7hXM.jpg" alt="enter image description here"><br>
<sup><em>Photo by <a href="http://tronixstuff.com/" rel="noreferrer">John Boxall</a></em></sup></p>

<h2>Which pins do they use?</h2>

<p>To determine if two shields are compatible, you have to read the specifications of both shields.</p>

<p>The best source for this information is the data sheets supplied with the shields. However there is also this <a href="http://shieldlist.org/" rel="noreferrer">Shield List</a></p>

<h2>Can you reassign pins?</h2>

<p>Some shields provide a means to alter which pins are used for communications. This can take the form of a switch or a jumper - either pull-off or solder-bridge type. (the GPS shield in the question has jumpers).</p>

<p>Where the shields do not support pin-reassignment or provides insufficient flexibility, to work-around incompatibilities you can use an in-between shield designed for the purpose.</p>

<p><a href="https://www.sparkfun.com/products/11002" rel="noreferrer">here</a> is one example:</p>

<blockquote>
  <p>You hear it all the time in the Arduino community, “will this shield work with my other shield?.” I think we’ve all been disappointed to find that two of our favorite shields compete for control of a digital pin here or a serial pin there. While there are sometimes some clever workarounds from elegant code modifications to aggressive ‘greenwiring,’ Mayhew Labs may have come up with the simplest solution thus far: The Go-Between Shield.</p>
</blockquote>

<h2>Are any alternatives for the foo shield</h2>

<p>I notice that Arduino.cc now point people to the list referenced above. They used to have their <a href="http://playground.arduino.cc/Main/SimilarBoards#goShie" rel="noreferrer">own list</a>.</p>

<p>Product recommendations are off-topic here but, obviously, you can <a href="https://www.google.com/search?q=gps+shield" rel="noreferrer">search</a></p>
