We wrote a few days ago that Tango was updating their video calling app for the Samsung Focus and Samsung Omnia 7.
The update has now reached marketplace and the app is now reported to work quite well on the Samsung Focus, including video calls with the rear facing camera. Unfortunately Samsung Omnia 7 owners are still having issues.
The company has however comitted to continue working to supporting as many brands of Windows Phones as possible, so I am sure a stream of updates will follow shortly.
The Tango video calling app can be found in Marketplace here.
Thanks Lalith for the tip.