Currently bundled JRE version is 1.7.0_50 which has an outdated tzdata (timezone data) library which makes time to be shown incorrectly. The latest Java 7 update should have most of the timezone issues fixed. There is also 1.7.0_75 (it contains mostly security fixes and 76 version has more bug fixes).
Linux is controlled via a bamboo configuration variable - updated.
Windows is controlled via install4j XML file option - updated.
Daryl, i can't assign Spark issues to you, but maybe you can also take a look at similar ?