In Plone 4 / TinyMCE there are only 3 image styles (inline, left and right).
These selections are hard coded in the plonebrowser template
If you want more styles, you can do the following.
With jbot, override the template, like this:
( the name of the template should be: Products.TinyMCE.skins.tinymce.plugins.plonebrowser.plonebrowser.htm.pt )
Add the relevant CSS
If you added a line like this:
<optionvalue="image-framed">Left with frame</option>
The CSS could be:
.image-framed {margin: 0 1em 1em 0;float: left;border: 1px solid silver;padding: 6px;}