Internationalized Domain Names
Many languages use characters not included in the ASCII code set native to most computers in the English speaking world. A new format for domain names has been developed to accommodate these languages.
The new URLs contain the string "xn--" followed by a combination of letters and numbers. This will appear in the browser status bar and in the address bar (except IE which has not yet been updated to handle IDNs and, for the moment, will error out if a URL contains non-ASCII characters).
There is a slight possibility of malicious URL "spoofing" by using characters from another language that are similar to ASCII characters.
If you encounter the xn-- format and the site is requesting personal or financial info, beware!