The SLTs do have mirrors, but they're mirrors that let the majority of the light pass straight through to the sensor, rather than having to swing out of the way to allow exposure. As a result they are fixed in position, always reflecting a portion of the light emerging from the back of the lens onto a phase-detection AF array housed in the top of the camera. (A newly-developed 15-point array in the case of these two cameras).The A55 and A33 look interesting, but of course I'm also waiting to see how the NEX-VG10 turns out...the idea of buying another brand of DSLR for video, doesn't really appeal to me, but if you're already in the Sony DSLR camp and want to do video, these look iteresting.
DPReview: Sony SLT Alpha A55 In-depth Review,* August 2010
Canon has announced an APS-H sized 120 Megapixel chip (though they aren't putting it in a camera just yet!) Meanwhile, Canonrumors is speculating that Canon may develop some cine-style PL lenses. (PL is the mount used by many 16mm and 35mm film cameras.) It seems odd that they'd bother making lenses for such a comparatively small market. I'd think they'd be more interested in producing cine-style lenses that fit on their own DSLR cameras, and prevent Zeiss from taking away some of the business.
Finally, IBC runs September 9-14 in Amsterdam, and there will probably be some announcements there. Panasonic is expected to announce the price and availability of their large-chip video camera, the AG-AF100, at the show. Some think that this - and cameras like the NEX-VG10 - will spell the end of the DSLR's days in the sun as video production tools. I'm not so sure, but time will tell. The more competition the better!
Panasonic microsite: AG-AF100