The exact date is not given, but since late August is the usual time when the event was held in previous years (for example 2008, 2009) - weekends of the last week in August to be exact, I would assume that it's going to be on the 28th (Saturday) and 29th. The venue is not mentioned.
Chara Hobby is an important event to look out for new Gundam merchandises. Gundam Expo Tokyo usually precedes Chara Hobby with one or two weeks of close gap between the two events, which makes the later a repetition in terms of new Gundam products. ^^; However, we do get more information regarding the many items at Chara Hobby. For example, in 2008, only the prototype of MG Infinite Justice (new item back then) was shown at Gundam Expo Tokyo, a completed model in full color was then showcased at Chara Hobby.
Last year was a different story though, as "Feel G" Gundam Big Expo, one of the three major projects for the celebration of Gundam 30th Anniversary ended just a few days before the start of Chara Hobby 2009, and Bandai rolling out everything about Gundam that they can at Gundam Big Expo, there weren't many new items from that genre to be seen at Chara Hobby 2009.
It's Gunpla 30th Anniversary this year, all of us can safely assume that the yet to be announced Gundam Expo Tokyo (or any other big Gundam event in August) is going to be really huge this year. What is the role of Chara Hobby in terms of Gundam merchandises then is the question to ask.
I suppose it all depends on Bandai for the arrangement then ^^;
However, in terms of importance, the highest tier always belongs to Shizuoka Hobby Show. ^^ It's going to be the 49th edition this year, coming in mid May.
Images from the official site.