Openoffice.org spellcheck doesn't seems to work on Ubuntu 9.04 Jaunty either. It's a well known problem that can be easily fixed but somehow it gets carried on from one release to the next. When you run a spellcheck, Openoffice immediately says that spell check is complete even when the document has mis-spelled words.
Openoffice.org uses hunspell so you better check if its installed. Secondly make sure that the default language is set correctly.
# apt-cache policy hunspell
500 http://jp.archive.ubuntu.com jaunty/main Packages
# sudo apt-get install hunspell
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
libyaml-syck-perl libftgl2 libchm1 python-chm libalut0 libindicate0
Use 'apt-get autoremove' to remove them.
The following NEW packages will be installed:
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 91.5kB of archives.
After this operation, 246kB of additional disk space will be used.
Get:1 http://jp.archive.ubuntu.com jaunty/main hunspell 1.2.6-1ubuntu2 [91.5kB]
Fetched 91.5kB in 2s (45.2kB/s)
Selecting previously deselected package hunspell.
(Reading database ... 190374 files and directories currently installed.)
Unpacking hunspell (from .../hunspell_1.2.6-1ubuntu2_i386.deb) ...
Processing triggers for man-db ...
Setting up hunspell (1.2.6-1ubuntu2) ...