As a follow-up to their previous update on Lion adoption numbers, The Omni Group has published a blog post on Omni Sync Server usage stats. The Omni Sync Server is a cloud-based system that handles OmniFocus databases across Macs, iPhones and iPads. It’s been in “beta” for several months and it’s free, allowing OmniFocus customers to keep their tasks in sync over-the-air free of charge.

The Omni Group monitored usage on the OSS, and found out that roughly 31,500 users were active in the past 8 days (at the time of publishing the blog post). 92% of iOS devices on the OSS were updated to the latest version of iOS, 5.0.1; the most popular Mac computer in usage logs has turned out to be the 2011 MacBook Air with 10%. As for OmniFocus, the majority of active users are opting for the Mac+iPhone combo, with “all 3” being the second most registered option. Surprisingly, “only” 2069 users were active as iPad-only.

With Omni Sync Server, The Omni Group has built its own cloud that syncs user data across the whole OmniFocus ecosystem on OS X and iOS. The developers have also confirmed that the service will come to other document-based Omni apps, such as the popular OmniOutliner. Indeed, the lack of proper automatic sync between the mobile and desktop versions of these apps has forced many users to either switch to different software with Dropbox support or rely on third-party tools such as DropDAV, which turns your Dropbox into a webDAV server compatible with Omni apps and Apple’s iWork for iOS (the latter lacking cloud sync before version 1.5).

You can read more about OmniFocus’ sync and the Omni Sync Server here.