I have not seen any examples of using OWA parts in an iFrame.  However, I wrote such a sample recently and wanted to share it.

The full OWA UI in an iFrame is not supported and its expected that doing so may fail at any given point and at different points depending upon the service pack and hotfix rollup.  You can use OWA Parts (a URL reference to a folder which displays content) in an iFrame.  OWA parts have several options for outputting the contents of a folder, however they do not provide the full functionality of OWA.   OWA Parts work off a URL which takes parameters to output the desired view of a folders contents rather than using a direct url reference.

I have seen some customers get OWA to mostly work in an iFrame by modifying the .js files to redo frame targeting – however, this is very much not supported in any way and any sort of update to the server may overwrite the .js file changes;  further, if there are issues with OWA, you may be required to reverse all such changes before support can be provided.

As an example, this:

https://127.0.0.1/public/test%20team%20calendar

Would need to be written something like this:

https://127.0.0.1/owa/?cmd=contents&module=PublicFolders&fpath=test%20team%20calendar

Here are some articles which you should review around developing with OWA in an iFrame or usage of OWA Web parts:        

Hosting Outlook Web Access in an IFrame Is Not Supported
http://technet.microsoft.com/en-us/library/ee221162(EXCHG.80).aspx
 

How to Use Outlook Web Access Web Parts
http://technet.microsoft.com/en-us/library/bb232199(EXCHG.80).aspx

Below is a sample iFrame I put together - it loads views of different folders for a mailbox and public folder.  You will need to change the server part of the URLs to match your server and create a folder called “abc” in your inbox and a folder called “test”and a calendar folder called “test team calendar”  in your public folder to use it.

<html>
<head>
    <title>test iframe with owa web part</title>
</head>

<body>

<iframe src="https://127.0.0.1/owa/?cmd=contents&fpath=inbox" name="OwaPartsSample" align=center height="500" width="900" scrolling="Auto">
</iframe>

<br><br>

<div align=center>
  <b>Test Links</b>
  <br>
  <br>

  <!-- reference Inbox -->
  <a href="https://127.0.0.1/owa/?cmd=contents&fpath=inbox" target="OwaPartsSample">Inbox</A><BR>

  <!-- reference Inbox/abc -->
  <a href="https://127.0.0.1/owa/?cmd=contents&fpath=inbox%2fabc" target="OwaPartsSample"> Inbox abc folder</A><BR>

  <!-- reference calendar -->
  <a href="https://127.0.0.1/owa/?cmd=contents&fpath=calendar" target="OwaPartsSample"> Calendar</A><BR>


  <!-- reference Public Folders/test -->
  <a href="https://127.0.0.1/owa/?cmd=contents&module=PublicFolders&fpath=test" target="OwaPartsSample"> Public Folder test folder</A><BR>

  <!-- reference Public Folders/test team calendar -->
  <a href="https://127.0.0.1/owa/?cmd=contents&module=PublicFolders&fpath=test%20team%20calendar" target="OwaPartsSample">Public Folder - Test Team Calendar</A><BR>

  <!-- reference Public Folders/test team calendar -->
  <a href="https://127.0.0.1/owa/?cmd=contents&module=PublicFolders&fpath=test%20team%20calendar&view=Weekly" target="OwaPartsSample"> Public Folder - Test Team Calendar - Weekly</A><BR>

  <!-- reference Public Folders/test team calendar -->
  <a href="https://127.0.0.1/owa/?cmd=contents&module=PublicFolders&fpath=test%20team%20calendar&view=monthly" target="OwaPartsSample">Public Folder - Test Team Calendar - Monthly</A><BR>


</div>
</body>

</html>

Remember that OWA will need to authenticate you, so you should have integreated authentication enabled when you use these URLs othersie you could well get an error.

Please note that item URLs are not supported in an iFrame. The OWA URLs you can get from EWS for displaying individual items are only supported when opened in new browser windows.  Only the URLs as described in the following article are supported:

How to Use Outlook Web Access Web Parts
http://technet.microsoft.com/en-us/library/bb232199(EXCHG.80).aspx

Also see:

Microsoft support policy for the customization of Outlook Web Access for Exchange
http://support.microsoft.com/KB/327178

OWA Single-sign-on support
http://blogs.msdn.com/b/webdav_101/archive/2012/08/07/owa-single-sign-on-support.aspx

Microsoft does not support using ISAPI extensions or filters to modify Outlook Web Access credentials on a server that is running Exchange Server
http://support.microsoft.com/kb/938609