If English Wikipedia IE8 users use the MediaWiki:Edittools.js to insert a character into the editor. They get an extra space character after the character they have inserted. This behavior started around February 10th, and present to users who are not in the Beta.
According to one user this problem does not present if http://bits.wikimedia.org/w/extensions/UsabilityInitiative/js/plugins.combined.min.js is not included into the source, which it is, even for non-beta people.
Version: unspecified
Severity: normal