Let's start with the Wiki and then delve into primary sources. A final summary answer is at the very end for the very impatient:
The Wiki for Star Wars canon says:
T-canon refers to the canon level comprising only the two television shows: Star Wars: The Clone Wars and the Star Wars live-action TV series. (src: SW Canon Wiki )
That statement actually derives from input from none other than Leland Chee, keeper of the Lucas's internal consistency database (Holocron) and the main authority on all things canon aside from Lucas himself.
From http://web.archive.org/web/20080819192442/http://forums.starwars.com/thread.jspa?threadID=152583&start=1348 :
Q: regarding the 3d clone wars cartoon and the live action star wars tv series, are they g-canon or c-canon?
A: So far I'm using the term T-canon for the upcoming animated series and live-action series. Nothing prior is being considered T-canon.
Now, the above is not very unambiguous as far as FUTURE work, but we can glean more from other Leland posts:
Leland Y Chee
Date Posted: Mar 11, 2008 02:00 AM
Undoubtedly T-level canon would be above C-level, primarily because of George Lucas's increased involvement. The secondary reason is that the the potential audience for the theatrical release and television run is likely to be many times greater than the rest of the EU combined.
Now we are getting there:
Any future possible TV series will be: