What would be the best approach to target marketing a FM Go solution to people who have purchased iPads?

I'm not sure that's the way to look at it.

You want to market your solution to people who will find it useful. If it keeps track of horse genealogy, you market it to horse people (trade mags, website advertising, get it reviewed by bloggers, etc).

Even though it is geared towards iPad users, you may not want to focus on just the techie marketing, as a growing number of iPad purchasers are not techies, but elderly folks who like the ease of use.

If it's useful enough, people may even buy iPads to use it!

Well, We can depend on the records of people that use the similar sofware on Iphone and Ipad. It can help us to appreciate the target market.

Get filemaker to reduce the price of fm go for iPad. At $40.00 its a good extension for some one who has a database and business logic or Home Setup that can make use of the ipad. Other wise iOS4 for selling targeted data management apps to the entire iPad market. Oh yes and better yet just make good web apps then no dev fees.