Short blurb on TBS's
Hidamari Sketch page on 22 November saying yes the fourth season will air in 2012. No world yet on in what season.
ひだまりスケッチ第4期は、2012年放送開始予定です。よろしくお願い致します！
(Fourth Hidamari Sketch is scheduled to begin broadcasting in 2012. Thank you!)
No real surprise there.
The art work posted 7 October is rather nice, too bad it has the big SAMPLE stamp on it.