Conversation so far:
What were some of CBC Radio 3's webcasts?
the Icecast stream.
When did Icecast start?
2005.
When did it end?
2009.
Why did it end?
Due to funding cuts.
What kind of content did Icecast have?
Initially, the webstream consisted exclusively of music with the occasional identification break.
Did they add more later?
it was relaunched with hosts and feature content, similar to but still programmed separately from the satellite radio station.
When did it relaunch?
September 14, 2007.
Did they do any webcasts after Icecast?
X3.
What was X3?
a new collaborative cross-promotional platform which sees all three outlets air feature content spotlighting a particular "Artist of the Month".
What 3 outlets?
CBC Radio 3 participated with Exclaim.

Question: When was this started?
Self-contained rewrite: When was X3 started?