I have used really long passwords in Excel (Office 2007 BETA).
My passwords are longer than 32 characters but not more than 64
characters.

Two issues with B2TR seem to have occurred:
1.) password length now limited?
2.) cannot paste password into 'Confirm Password' dialog?

Here's how I have been protecting Sheets (not Workbook):

With the sheet I wish to protect in front and visible,

I select 'Review'

Then I select 'Protect Sheet'

'Protect Sheet' dialog appears.

I can paste my really long password.

Click [OK].

'Confirm Password' dialog appears.

I cannot paste the long password.

Even still, if I begin to type the password, it will not let me type
beyond 15 characters.

Tell me where I am going wrong here.

Can someone refer me to on-line documentation about this.

(Right group for this kind of question?)