Images with the 'thumb' parameter are currently rendered with a frame and an icon labelled "Enlarge" that links to its description page. Unfortunately, the current icon http://meta.wikimedia.org/skins-1.5/common/images/magnify-clip.png is really not self-explanatory and doesn't indicate that more information can be found by following the link. In particular, no indication of how to get information about the image licensing is given. This causes attribution issues, since many visitors have no clue about how to reuse the file or who the author is (we regularly receive emails about this on Wikimedia OTRS).
- New symbol
This issue was recently discussed on the mailing list for Wikimedia Commons. It was proposed to replace the current icon by a white lowercase 'i' on a blue background; this is globally recognised as a symbol for a source of information (http://www.bristol.ac.uk/imagelib/i.html). Some public-domain images meeting these requirements are available on Wikimedia Commons http://commons.wikimedia.org/wiki/Image:Information_icon.svg. One of them could be used a a replacement of the current "magnify-clip.png" image.
- New label
There is an existing MediaWiki message for the word "Information" http://meta.wikimedia.org/wiki/MediaWiki:Info_short. This message could be used as a replacement for the label "Enlarge", or both words could be used as the label, e.g. "Enlarge / Information".