Microsoft has begun rolling out a new firmware update for the Surface Pro 3, which is the first to be made available since early November, when the company fixed some battery issues. The update says "System Firmware Update - 1/30/2017", and that's all that we know about it.
As is the case almost always, there is no changelog available. Indeed, Microsoft continues to struggle with publishing release notes at the same time as offering the update. Along with all Surface firmware updates, this also tends to be the case with cumulative updates to Windows that are offered through the Release Preview ring of the Insider Program.
While there must be some great technical difficulty in getting these notes out in a timely fashion, rest assured that they will be published at some point, likely between 24 and 72 hours from now, if history is any indication. When they are available, you can find them here on the Surface Pro 3 update history page. Of course, we'll keep you updated as well.
Update: The changelog is now available.