In the plupload module's plupload.js, IE throws the following error:
SCRIPT1004: Expected ';'
plupload.js?m1kcz7, line 84 character 21
This is due to the following code:
//@todo Implement a setting for whether the field is required, rather
//than assuming that all are.
The culprit is that IE is trying to interpret @todo even though it is inside a comment. Removing the @ solves this issue.