Current Requests were either submitted using the cgi web interface before it had to be removed (September 2007) or via email to the embedding-hn hypernews list.
As such there is not a single source of information. The excel spreadsheet here is a summary of the known requests as of August 2008 (also pdf printout for those without access to excel). The co-ordinator should keep this updated.
Heavy flavour have also kept an up to date page with their extensive list of requests. See here.
[The spreadsheet was part of a presentation (ppt|pdf) in August 2008 on the state of embedding at the end of my tenure as EC - Lee Barnby]