A colleague tells me that details of today's Budget are available from here.
Including a link to DirectGov from where, "You will be able to view the speech live from this page in either Windows Media or Real Player formats, as well as download an audio 'podcast' version for use on your PC or MP3 player."
Just what I wanted!
This is not the only example of high tech government I've seen lately. It seems that the Office of the Deputy Prime Minister, which ran an experimental wiki for a while, now has a blog.