We're already planning a feature along these lines, however the only way I could see it working is by making it an autoDJ-only feature and allowing the client to mark certain playlists as "do not show metadata".
If you're broadcasting live or via a relay, Centova Cast has no real way of identifying which metadata coresponds to a jingle/ad and which corresponds to a song. heisenberg's suggestion is probably the cleanest one, but failing that, all we could really do is give the admin the option to filter certain metadata strings based on a pattern -- eg: if the metadata contains the word "advertisement" or "jingle" it could suppress it.
We could only apply such filtering to the song information displayed in the Centova Cast widgets, though -- your SHOUTcast/IceCast server itself WOULD continue to display the jingle/ad metadata, simply because your live source/relay connects directly to the SHOUTcast/IceCast server, so Centova Cast has no way to intercept and filter the metadata. If you need to block that as well, then you'd need to investigate heisenberg's suggestion.