Okay. This was announced a month ago but I just saw the news in their official website.
The Sketchbook Project was launched in connection to the anime Sket Dance due to its popularity because of the episode with the Kaimei Rock festival where the three main characters (Bossun, Himeko and Switch) formed a band, which was eventually called the Sketchbook. After an audition to gather similar members the real-life version of the band consists of three members in total: Tada Hiroshi (多田宏) on bass and vocals, Kohara Riko (小原莉子) on guitar and Watabane Yuu (渡邊悠) on drums. Their debut single was Michi (道), released on September 28, 2011. - last.fm
When I heard the new song Birthday after watching the Bossun-arc, I was really happy to know that the sketchbook is back with a new single. They've been releasing new singles one after the other but I'm not really complaining or anything. Anyway, last episode52, I was really happy to hear again the new ending theme of SKET Dance which is Colors and it was also by the sketchbook. The new single will most likely feature the two new songs together with their instrumentals. The single will be released on May 30, 2012 :D Further news will be posted soon.