The dissolving of parliment is standard procedure leading up to general elections. The exact time it can be done is somewhat flexible though and timing it right can be crucial. The general opinion is Aso waited too long and things are going to go badly for his party.
The Liberal Democratic Party has been in power since the modern Japanese government was formed after world war 2 and that may change next month. Aso has been a complete train wreck, Fukuda before him was a bad joke and Abe would have had to improve a lot to even qualify as inept. I foresee the LDP losing power to the Democratic Party of Japan this august. This has serious ramifications on me as my job is based on American military presence in Okinawa, something the DPJ is keen on tinkering with. The communist party is gaining ground as well but I don't think will have a tremendous impact.
Some english media sources in Japan that may help you follow this potentially historic event.
http://www.japantimes.co.jp/http://mdn.mainichi.jp/
The websites for the major parties.Liberal Democratic Partyhttp://
www.jimin.jp/jimin/english/
Democratic Party of Japanhttp://
www.dpj.or.jp/english/
New Komeitohttp://
www.komei.or.jp/en/
Communist Partyhttp://
www.jcp.or.jp/english/