In 2007 we introduced spinner.gif as an animated progress indicator, currently used in some of the AJAX data fetching for uploading, CodeReview, and probably a few others.
The icon itself is a little funky looking IMO; per log it was originally intended to visually reflect the MediaWiki flower logo (ie, with little yellow petals) but this doesn't really come through. More importantly, it's not visually clear on some backgrounds and it doesn't fit with our visual style as we're modernizing it with the Vector skin etc.
I'd recommend something with more of a modern look, perhaps like this Tango-themed throbber:
http://commons.wikimedia.org/wiki/File:Loader3.gif
or this Ubuntu-style one:
http://commons.wikimedia.org/wiki/File:Linux_Ubuntu_Loader.gif
Assigning initially to Parul as part of our visual refresh, but anybody feel free to pile on some notes. :) [If there's not a clear winner let's slap up a page on usability.wikimedia.org w/ some ideas.]
Version: unspecified
Severity: enhancement
URL: http://www.mediawiki.org/skins-1.5/common/images/spinner.gif