Here are the following steps to reproduce this bug:

1. On a Wiki space, click on "Add" -> "Page" or "Blog Post".
2. Use the following sample Wiki markup:

   h1. {color:#800000}HohohohoHOHOooHohoHoHoHo~\!{color} !toy-story-buzz-lightyear-wallpaper-2560.jpg|border=1,align=right!
   merry xmas
   

3. Click on Preview tab.
4. The image is rescaled to small size and aligned to the right.
5. When you click on Rich Text tab, the image is still showing its actual size.

This bug is reproducible using Default/Documentation Theme and it is also happening in both Firefox 3.6.10 and IE 8.