I have been following the with interest for the past 5 years!! Well done Apple!!!
This is a joke - i bought my iMac in 2009 with a view to editing high quality home video HD footage and after MANY enquiries with Apple Tech Support was given the resounding disclosure that "iMovie is just a toy bundled for free.... if you want something better then you need a better program!!!".
Sp here we are, another update from Apple saying that AVCHD is now supported (albeit much later than Windows based products which I had to resort using through bootcamp on the iMac) and still now it exports to MP4!!! Will this ever be something good?