First spotted by Chicago-Joe yesterday evening, SGI has released IRIX 6.5.23. The announcement is here
It's not possible yet to download it via supportfolio, but the software orders section has already been updated with the new IRIX.
Please note that there is no support anymore for older systems (<=IP26 and IP28. IP27 is an early O200 model and is supported, thanks Michael) . I quote:
Changes to Support Mode Status
The following workstations, graphics and scalable server systems have transitioned to retired support mode for the IRIX 6.5.23 release. IRIX 6.5.23 does not support installation on these systems.
Challenge� S, Challenge� M, Challenge� DM, Challenge� L, Challenge� XL
Indigo�, Indigo2�, Indigo2 Extreme, Indigo2 Impact�
Power Challenge�, Power Indigo2�, Power Onyx�
So save your irix 6.5.22 CD's. They come in handy when an Onyx drops in your lap :)