I found a way to make Pinnacle Studio 10 import MP4 movies (encoded with avc1 H.264/MPEG4 as reported by GSpot).
My Sony T90 camera creates High Def videos and I needed Pinnacle to read them.

1. Download and install the Pinnacle H264 Codec => files/12472894...C.v2.0.527.rar
NAV thinks it's a virus, but apparently not; so you may have to disable it for a while.

2. Run the normal install Pinnacle.H264.CODEC.v2.0.527.exe

3. Now the problem is, the installer forgot to copy the codec into the programs directory:
copy "C:\Program Files\Pinnacle\Shared Files\Filter\H264Codec.ax" "C:\Program Files\Pinnacle\Studio 10\programs"

That's it. Now start Studio 10 and browse for an MP4 H264 video file; the thumbnail should now populate and be able to be dragged to the timeline.

- Steve