I have the same problem when installed mediawiki to Fedora 4, too.
Furthermore, I encontered "The file is corrupt or has an incorrect
extension. Please check the file and upload again." error.
Is there you encounter the same problem?
> Message: 4
> Date: Thu, 19 Jan 2006 11:29:39 +0100
> From: Magne Westlie <magnew(a)simula.no>
> Subject: [Mediawiki-l] Images don't show anymore, only "Image:
> foo.gif"
> To: Mediawiki mailinglist <mediawiki-l(a)Wikimedia.org>
> Message-ID: <1137666579.16284.57.camel(a)localhost.localdomain>
> Content-Type: text/plain
>
> I'm having a problem with my mediawiki.
>
> I've moved my mediawiki to a new server, and everything works fine,
> except that the embedded images does not show anymore. They actually did
> at first, but when I tried to upload an image, I noticed that I had to
> give the apache-user write access to the 'mediawiki/images' folder to be
> able to upload. So I did just that, and after this change no images are
> shown anymore, only the "Image: foo.gif" text which is a link to the
> image page, which also do not show the image, only the metainfo for the
> image. I've tried to revert the changes I did after the images did not
> show anymore, but they still do not show. If someone could help me with
> this i would be very glad, as the images are a vital part of the
> information that are kept in my wiki.
>
> Just to make myself clear: I still find all the images in a subdirectory
> of the 'mediawiki/images' folder, they're just not shown in the pages.
>
> Thanks!
>
> MediaWiki 1.4.13
> PHP 4.4.0-4 (apache2handler)
> MySQL 4.1.15-Debian