According to ISO 8601 and NEN 2772 the week that starts on monday the 16th of august should be week 33 this year.
Greenhopper states this is week 32.

Therefore the bug is: week numbers are wrong

This is a problem for me because: It makes it hard to communicate about week numbers when different tools use different week numbers. Outlook 2010 does it right, why can't we?

There may be more than one week standard out there that people want to use. Perhaps there is a good reason that Jira is currently not using the standards I mentioned. In that case this is not a bug but a feature request. In that case: please add a way for admins to choose the week numbering standard that they wish to follow.

to reproduce:
log in with admin rights for atleast one project
go to a project which you have rights for
click 'administer project'
click 'manage versions'
click the calendar for the 'release date'
compare week numbering with outlook 2010 and/or ISO 8601 and NEN 2772 numbering