As you know, ie7 doesn't support £.com or €.com showing them as punnycode.
Safari and Opera have no problems because they don't care about the language script encoding. € and £ are on the "Zyyy" (Common)... that's were the problem is.
http://www.unicode.org/Public/4.1.0/ucd/Scripts.txt
My question to Microsoft was:
Would the ie team ever open exceptions on the unicode definitions due to certain languages specific encoding issues (maintaining the phising barrier, of course)?
And their answer:
It's possible that certain characters will be permitted to mix in a future release of IE. This depends on a variety of factors, including future standards, the phishing environment, and the user-scenarios that such a change would enable.
Thus, I have created this thread.
Use it to post what characters and why you think should be accepted.