The script is still being finished. Cass Browne, writer of the Gorillaz dialogue, has mostly been working on the script while Jamie Hewlett has been concentrating on final preparations for Monkey the Chinese Opera (more info on Monkey on Wikipedia here)
The movie has undergone a substantial re-write, to the extent that some details given in the Gorillaz-Unofficial interview with Cass and Jamie in October 2006 (which can still be read here) are now inaccurate. Everyone involved with the film is really enthusiastic about the changes and thinks they will really make the movie a lot better. However the details are confidential at this stage.
The movie will have an accompanying soundtrack album.
Nobody involved with Gorillaz is thinking beyond the movie and it is not known what future projects Gorillaz might be involved with after the movie. It is certainly not the case that future albums have been ruled out completely.
Keep checking Gorillaz-Unofficial.com for all the info as we have it. In the meantime, enjoy a rarely-seen interview with Jamie, from the DVD-magazine SpecialTen issue January 2005.