Micro Four Thirds cameras such as the Olympus E-PL1 and Panasonic Lumix DMC-GF1 pride themselves on being smaller in size than dSLRs, and that's due to the removal of the mirror components. However, this implementation means such shooters can utilize only contrast-detection autofocus (AF), which is slower than phase-detection AF found on dSLRs.
A recent patent by Panasonic revealed that the company appears to be working on an adapter that'll allow phase-detection AF in Micro Four Thirds cameras. This attachment fits between the snapper's body and the lens. It seems that within the attachment, there's a low-pass mirror that allows most light to filter through, while reflecting some to a phase-detection module below.
If this patent becomes a reality (bearing in mind that not all patents make it to market), I guess we'll see faster-performing Micro Four Thirds cameras on shelves. Also, it's great that it's an optional accessory, so advanced users who need faster AF can get it, though at the expense of making the camera more bulky.
(Source: Crave Asia via 4/3Rumors)