Rumour has it that the N900 will soon have a new firmware in the form of v1.2009.41.13 that will be available via the Nokia Software Updater. Looking at the number of the firmware it seems that v1 stands for version 1, 2009 for the year, 41 for the week and 13 for the day. Counting backwards this seems to suggest that this build is just a week old and may be the release that ships on retail N900’s.
The source of these rumours was a Nokia Support Discussions post, which has now been removed, but a Google search still shows these results. The removal of the post is what makes this rumour interesting. Please keep in mind that these are all speculations and v1.2009.41.13 may turn out to be a build that is never released or one of the many used for internal testing.
But if this is the retail release, the N900 will be on track for a late October/early November release.