I'm sorry that you weren't able to get a clear answer to your question via our support channels.
We ran a time-limited special offer that provided purchasers of Web Premium CS4 with an opportunity to get a license for Flash Builder 4 Standard. With the release of CS5 the existing Web Premium CS4 offer expired, hence why the site you referenced is no longer accessible.
Even though you are outside the offer redemption period, we will provide you with a license key for Flash Builder 4 Standard. Please email me (shorten at adobe.com) with your CS4 serial number and I'll forward you a serial that will work for Flash Builder.
Senior Product Manager, Flash Builder
Andrew-- I just sent you an email using the email address on my account and included the CS4 serials. Let me know if you don't receive. Thanks for the quick response!
I know that this is well outside the time-limited special offer but was wondering if it would be possible to get a serial number for Flash Builder CS4 as we have Web Premium CS4.
Thank you in advance.