The developers have been actively squashing bugs and adding some new features over the last year.
http://www.omnigroup.com/products/om.../releasenotes/
I wouldn't call this a dead horse when it is still being worked on.
as @rmathes said, the iPad, iPhone, and Mac apps are all still being actively worked on.
Now you may think "why are they wasting their efforts on version 1.x and just get on with version 2.0?"
There may be some of us who are happy with version 1.x and may not want to go to Version 2.0 just yet until the dust is settled.
If version 2.0 will be a radical change in user interface and user experience, it may be too jarring for some of us to change our workflow until we've had time to transition on our own schedule and not another software company's release schedule.
A perfect analogy is Windows 8. There are many people who are still working in Windows XP and Windows 7. Windows 8 is the newest version but many folks don't see the need or have the desire to upgrade to Windows 8 until the dust has settled and bugs are squished. Heck, some IT departments have finally just started transitioning to Windows 7. They could care less about Windows 8 until there is a program that really requires Windows 8 to work.