The company is promising a new version of the software, and updates to a cloud platform and hardware reference designs intended to make it easier to prototype products.
The version of mbed OS that will go on show this week, though, is not the final release developers were expecting.
Chances are your cellphone contains a core or four designed by ARM, as its Cortex-A design has been adopted by Apple, Samsung, and a host of others.
ARM also a more power-efficient family of designs, the Cortex-M microcontroller series, intended for battery-powered embedded and wearable devices.
In September 2009 ARM launched an online development platform, mbed, to make it easier for developers to create new devices using its microcontroller designs. These days they're turning up in things like the FitBit or smart watches.
Initially the mbed tools worked with only one chip, NXP's LPC1768, but over time ARM added support for microcontrollers from other Cortex-M licensees.
Then in October 2014 the company announced that, as of Version 3.0, the platform would be called mbed OS. The new name marked a top-to-bottom redesign, ditching support for existing hardware development boards, with manufacturers having to reapply for certification on the new platform.
At the time, ARM published a development timeline, with Version 3.0-beta scheduled for August 2015 and the final release in October. In December we were to expect Version 3.1.
But August came and went with no beta release, and a marked refusal by ARM staff to answer questions about progress in the ARM forums.
By the time the beta version arrived in September, it had been renamed "mbed-OS 15.09 September 2015 Beta Release" as the company switched to the year-dot-month versioning system used by Linux distributions such as Ubuntu.
Meanwhile, timeline had been quietly erased from the company's blog.
Now the company is putting the finishing touches to mbed-OS 15.11 -- but this is only a "Technology Preview Release," not the final version, and the "mbed OS readiness" page of the company's website says there will be three more phases before a stable version is reached.
While developers wait for the final release of mbed OS, they will at least be able to play with some new features in mbed Device Connector, which allows them to integrate up to 100 prototype devices sending up to 10,000 events per hour to cloud services for free.
ARM has also created two new reference designs with support for mbed OS, one for wearables and the other for smart cities.
The wearable design is an interactive bracelet with an eight-week battery life, while the smarty city device is intended for infrastructure monitoring mesh network.