Joining the previous ULTRA adapters announced in September, these new adapters combine very high precision optical elements to improve the performance on Micro 4/3 cameras, and essentially replaces the version 1 MFT Speed Booster for only a little more money. This adapter shouldn't be confused with the newer Speed Booster XL 0.64x adapter announced a few months ago that was specifically designed to work with the Panasonic GH4 (this ULTRA adapter should work with any MFT mount camera). It's also worth noting that while pretty much all full-frame lenses should work fine, some Canon crop sensor EF-S lenses can protrude too far for the glass inside, so you should check out the Metabones site for whatever adapter you're using just to make sure. B&H is saying August for the Nikon to MFT ULTRA and October for the Canon to MFT ULTRA, but it looks like you can get the Canon one from the Metabones store right now.

They also announced a new firmware update (Windows/Macthat gives previous MFT adapters the ability to autofocus with Canon lenses, which is huge for folks who want to take stills with their EF mount lenses on Panasonic cameras. 

This is how pricing shakes out for their Canon and Nikon to MFT adapters (can't seem to find the product page on the Metabones site for the Nikon to MFT ULTRA, but it's listed on B&H):

Here's a little bit from their press release:

Like the revolutionary original Metabones Speed Booster® announced in January 2013, the Speed Booster ULTRA m43 has a magnification of 0.71x, and so it effectively reduces the crop factor of mirrorless Micro Four Thirds mount cameras from 2.0x to 1.4x.  However, the new ULTRA design makes very effective use of exotic materials at the furthest limit of glassmaking technology, and as a result is almost perfectly corrected for use with all fullframe SLR lenses regardless of aperture.  The Speed Booster ULTRA m43 will also work extremely well with many DX and APS-C format lenses provided the image circle of the lens is large enough.  Optical performance of the new Speed Boosters is so good that the MTF of any lens attached to it will be improved.  Even the latest generation of ultra-high performance SLR lenses such as the Zeiss Otus series can be improved by adding a Speed Booster ULTRA m43.

Obviously they have some charts to back up these claims in their press release, though your milage may vary in terms of how much of this sharpness you'll really see if you compared it to the old adapter. Apparently sharpness at wider apertures hasn't been affected:

And other aspects of optical performance haven’t been sacrificed in order to obtain high MTF, either.  Figure 5 shows that there is less than 1 stop of corner illumination falloff even wide-open at f/0.9. There is no vignetting at all after the output aperture reaches f/2.82.  Figure 6 shows that rectilinear distortion added by the Speed Booster ULTRA m43 is negligible at less than 0.7%. The charts shown in Figures 2 through 6 below show the optical performance of the Speed Booster ULTRA m43 when mounted behind an ideal “perfect” lens.

It's a bit hard to find comparisons between different Metabones versions, but this video from Tom Antos explains exactly what's going on with these adapters:

Since this is all a bit confusing, here's a chart showing compatibility with a few of the different Canon EF to Micro 4/3 Speed Booster versions:

Metabones Speed Booster EF to MFT Compatibility List

Autofocus on Panasonic Bodies

Here's more from the press release on the new autofocus capabilities with Canon Speed Boosters:

New in Speed Booster ULTRA for Canon EF Mount to Micro Four Thirds is autofocus on Panasonic camera bodies, subject to certain limitations (see specifications for details). We are pleased to report that Panasonic Micro Four Thirds camera bodies are capable of autofocusing accurately even if the maximum aperture of the Speed Booster and the lens combined is in the sub-f/1.0 range. Although our first and foremost priority is accuracy, we are able to make great strides in autofocus speed as well, which is significantly faster than a DSLR Four Thirds lens on a Panasonic Micro Four Thirds camera (with adapter), or our E-mount offerings on Sony cameras prior to Alpha 7R II. For existing Metabones patrons with any previously released Canon EF to Micro Four Thirds mount Speed Boosters and Smart Adapters, a firmware update (Windows/Mac) to add autofocus is available for download on Metabones' web site.

Speed Booster XL 0.64x Footage

We've got some footage and reviews of the second most recent adapter, the XL, which is primarily designed to work with the GH4. It uses similar glass as the BMCC adapter, but it's designed to work better with the GH4, and give you a nearly full-frame look when you're shooting HD (and far less of a crop with 4K):

For more, and to buy any of these adapters, head on over to Metabones, and you can also check out B&H.

Metabones Speed Booster — B&H

Metabones Canon EF to MFT Speed Booster ULTRA

Metabones Autofocus Firmware Update (Windows/Mac)

Source: Metabones