Please use my custom field type. It is more flexible –> http://www.hezser.de/blog/archive/2009/02/25/custom-field-–-upload-files-and-images.aspx

I updated my Wiki Webpart. For all of you who don't know what it does:

The normal Wiki Edit Form misses the ability to upload pictures. My Webpart, which has to be included to the EditForm.aspx, allows you to upload a picture. It also creates a link in your Wiki post, which displays the uploaded image.

This release of the Webpart is multi lingual. Meaning it will present text to the user in english and german. If you would like this Webpart in your language, drop me a note :-)

Installation steps:
(If you need help: look here)

1. copy the dll to the bin folder of your SharePoint virtual server
2. create an entry in the safecontrol section of your web.config
   <SafeControl Assembly="WikiWebpart, Version=1.0.0.0, Culture=neutral, PublicKeyToken=b17a955c3eada4c1" Namespace="WikiWebpart" TypeName="*" Safe="True" />
3. change the TrustLevel in the web.config to either "WSS_Medium" or "Full"
4. add the Webpart to the Webpart gallery of your sitecollection
5. modify the EditForm.aspx of your Wiki Page with SharePoint Designer, and add the WikiWebpart beneath the standard EditForm Webpart
6. you are ready to use it ;-)

  Download the Webpart

Update 23. Apr 2008:

I have released a new version. Bugfixing only.