The JSF tablib doc for this attribute still states "This property appears to have no purpose at all. It certainly has no documentation."
It's actually a pretty important attribute for file upload.
ex: <t:inputFileUpload id="myUploadFile" accept="application/pdf,image/*" ...
Maybe update to something like... "This attribute specifies a comma-separated list of content types that a server processing this form will handle correctly. User agents may use this information to filter out non-conforming files when prompting a user to select files to be sent to the server (cf. the INPUT element when type="file")."
(above was copied the above from w3c spec - http://www.w3.org/TR/html401/interact/forms.html#adef-accept)
ps. I'm using Tomahawk20-1.1.10 with myfaces 2.0.4 on tomcat 6.0.18. It honors the 'accept' attribute.