Project Web access tab is blank when you double-click a Project Server 2003 Outlook calendar item

Difficult for me to relate as I have not even beta tested what you are doing. Best I could say is to open Terminal Services Configuration>Server Settings and under Permission Compatibility switch from Full Security to Relaxed Security for legacy application support. If that works then you know you have a group policy misconfig or you should write a server script to allow Project Web to run scripts on client machines.

It's alway been on Relaxed Security.  Anything else I could try?

Did project web access create a virtual website or take over 'Default Website'? If you hop into IIS manager and poke around in the websites properties there is a setting that allows all client scripting. Also, you may want to go into Control Panel>Add/Remove Windows Components and load up ASP.NET support and CGI scripts support. Just a shot in the dark as Project Server should have already done that.

Got it working finally.

Excerpt from http://support.microsoft.com/default.aspx/kb/302003:

To enable VB Script support for Outlook forms when running Outlook 2007 on a Terminal Server computer, do the following:
1.      Install Outlook 2007 as a standalone application or as part of a 2007 Office suite.
2.      Determine the globally unique identifier (GUID) for the product that you just installed. If you installed Outlook, use that product GUID. If you installed Office Enterprise 2007, use that product GUID. For more information about how to determine the GUID of the product that you installed, click the following article number to view the article in the Microsoft Knowledge Base:
928516 (http://support.microsoft.com/kb/928516/) Description of the numbering scheme for product code GUIDs in 2007 Office suites and programs
3.      After you have the product GUID, run the following command line:
msiexec /i <Product Code GUID of [SKUName]WW.msi> ADDLOCAL=OutlookVBScript /qb
Note In this command, <Product Code GUID of [SKUName]WW.msi> is a placeholder for your product GUID.

For example, if you have Office Enterprise 2007 installed, your product GUID would be the following:
{90120000-0030-0000-0000-0000000FF1CE}
Therefore, the command line should appear as follows:
msiexec /i {90120000-0030-0000-0000-0000000FF1CE} ADDLOCAL=OutlookVBScript /qb