In Joomla! 1.0 backend a specific area (Static Content Manager) is available to create / edit the so called static content items, i.e articles that are not assigned to any section or category. The Static Content Manager has been removed from Joomla 1.5, does it mean that creating static content is no longer possible?

Absolutely no. The concept still exists, but in Joomla! 1.5 this kind of articles are more correctly defined as uncategorized content and can be created from the Article Manager as any other article.

When you are on the article creation / editing page, simply select Uncategorized from the section or category drop-down list. Save and your uncategorized (or static if you still prefer old name) article is ready.

As usual, you will need to go to the Menu Manager and create a link to the article to make it visible.