*I* can’t help. One of the plugins (most likely JetPack) has to change their code.
But that solution was based on the fact that SFC was causing conflicts.
If you’re not using SFC and still having issues, it will help the developers to know what version of WordPress you’re using and what theme you’re using. And active plugins, too.
I recommend holding off on using that contact form until Jetpack is updated with the filter/action suggestion from Otto (if that is, in fact, the plan). See if that fixes it. Then check back in here if it’s not.
On a semi-related note, the issue I was having with Contact Form 7 (after sending, there was no confirmation message), was solved by deactivating WP Super Cache. Hmph.
I’d still prefer to use an “official” contact form for some of my sites, but one thing that will keep me tied to CF7 is the ability to attach files in the email. This is a feature I’d like to request for the Jetpack form, while it’s being improved.