We offer free updates to all our products. For example, OmniFocus 1.1 is a free update to 1.0 and offers some major new functionality with the ability to synchronize your database. (It also adds archiving and some new style preferences, so hopefully there's something in this release for everyone.)
When the time comes for us to release a new major upgrade (i.e., OmniFocus 2.0), we plan to offer existing customers a substantial discount on the new version just as we do with all our other applications. On the desktop side, of course, we control our own store and we know that we can offer discounts as we already do.
The only wrinkle is we don't know whether this sort of upgrade will be possible on the iTunes store, but we've already expressed the need for this to Apple (months ago!) and we hope they'll have this in place by the time we have a 2.0 release. (That's still quite a ways off, so they do have some time!) If this is important to you, too, I encourage you to send Apple some feedback requesting this as well.
I hope this clarifies things somewhat!
What is the general product roadmap for OmniFocus?
We know what is in 1.1 from the SneakyPeak,
But what features are you planning for future point releases, how many do you intend releasing, and what are their planned release dates?
What are the big ticket items planned for v2, and when are you planning that?