Hmm... someone mentioned the same issue on Twitter. I hope this isn't the start of an epidemic!
If you have a Mac also connected to iCloud, it would help to see what the actual items look like on the calendar server, before OmniFocus captures them.
[If you don't have a Mac connected to iCloud, there's still a couple things we can try. Do not despair!]
If you do have said Mac, please try the following:
1) On the iPhone: To keep OmniFocus from capturing anything, make sure OmniFocus is not running in the background, by following these steps:
http://www.tuaw.com/2010/06/30/iphon...apps-in-ios-4/
2) Tell Siri a reminder just like you usually would. (But please use some silly action you don't mind sharing with us.)
3) Go fix yourself a cup of tea or do something else for a few minutes to let the iCloud syncing happen.
4) On the Mac, launch iCal and choose "Show Reminders" in the View menu. Make sure your silly action shows up.
5) [Still on the Mac] Now we want to find the actual file containing that action. Use Spotlight (the magnifying glass in the upper right corner of your screen) to search for your action by name. Choose "Show all in finder" from that menu. This will open up a new finder window, and your reminder should be one of the files listed there.
6) Open that file we just found in TextEdit or a similar app, so that you see text like "BEGIN:VCALENDAR". You can paste the whole contents here on the forum, or send it to us in an email (omnifocus@omnigroup.com). If you email it, please also include a link to this forum post so the Support Ninja knows what's going on.