Conversation so far:
What were some of CBC Radio 3's webcasts?
CBC Radio 3 's webcasets were Sessions
When did CBC Radio 3's use of Icecast start?
From 2005 the Icecast stream was available from CBC Radio 3's website
When did CBC Radio 3's use of Icecast end?
CBC Radio 3's use of Icecast ended in 2009.
Why did CBC Radio 3's use of Icecast end?
CBC Radio 3's use of Icecast ended due to funding cuts. However, the two services, Icecast and the radio program, were merged in June 2009.
What kind of content did CBC Radio 3's show Icecast have?
Initially, the Icecast from CBC Radio 3 consisted exclusively of music with the occasional identification break.
Did CBC Radio 3 add more content to their Icecast later?
The CBC Radio 3 Icecast was relaunched with hosts and feature content, similar to but still programmed separately from the satellite radio station.
When did CBC Radio 3's Icecast relaunch?
On September 14, 2007 CBC Radio 3's Icecast was relaunched
Did CBC Radio 3 do any webcasts after Icecast?
In February 2009, CBC Radio 3 participated with Exclaim! and aux.tv to launch X3.
What was CBC Radio 3's X3?
CBC Radio 3's X3 was a new collaborative cross-promotional platform which sees all three outlets air feature content spotlighting a particular Artist of the Month.
What other two outlets did CBC Radio 3 participate with to launch X3?
CBC Radio 3 participated with Exclaim! and aux.tv to launch X3

Question: When was this started?
Self-contained rewrite: When was X3 by CBC Radio 3, aux.tv, and Exclaim! started?