Adobe posted Illustrator CS4 Help on the Web in English a few weeks ago. (Here’s a link to the “What’s New in Illustrator CS4” section.)
Now, the localized (i.e., translated) versions of online Help are available in German, French, Italian, Dutch, Chinese, Danish, Swedish, Spanish, and Korean.
German: Verwenden von Adobe Illustrator CS4
French: Utilisation d’Adobe Illustrator CS4
Italian: Utilizzo di Adobe Illustrator CS4
Spanish: Uso de Adobe Illustrator CS4
Dutch: Adobe Illustrator CS4 gebruiken
Chinese simplified: 使用 Adobe Illustrator CS4
Chinese Traditional: 使用 Adobe Illustrator CS4
Korean: Adobe Illustrator CS4 사용
Danish: Bruge Adobe Illustrator CS4
Swedish: Använda Adobe Illustrator CS4