Following discussion on metadata list started by Anna Milan inspired by GeoSpatial Platform roadmap statement "The highest priority identified by 42% of agencies was a *metadata editor *that is FGDC compliant, web enabled, flexible and customizable. (p.37) "
Subsequent discussion pointed out that it is very useful for metadata production tools to be able to scrape information from datasets that are being described (e.g. the way ArcCatalog 9.3 scrapes information from a feature class), and thus needs to be running in a user space from which the data can be accessed by the metadata tool (typically not the case for a web app).
Perhaps what people are really looking for is a standardized user interface for producing and editing metadata, such that from the user's perspective, they create metadata through the same interface, whether the tool is running locally and scraping information from files on their computer, or over the web and they have to plug in everything manually. The objective is to keep reduce the amount of training/retraining that must be done.
From this point of view, the 'standard' metadata creation user interface should present a content model that is independent from any particular metadata standard. Tool designers would connect this interface through a data access layer to whatever metadata standard and encoding was required in a particular situation.
An example of this approach can be seen at http://mw.usgin.org/. The user creates metadata content that can be exported in csw:record (dc), FGDC or ISO xml through a single interface.