Here's what I saw at Oshkosh:
Continental introduced their CD300, which is based on a Mercedes 3.0L 300 hp, but heavy. still needs development. Is flying in a Cirrus SR22 (I saw it in Germany in Feb.) They also displayed their CD230 (formerly the TD300), which is the flat 4 230 hp engine being developed from technology purchased from SMA.
Engineered Propulsion Systems (EPS) had their 4.4L flat 8 350 hp engine there, and there's one being tested in a Cirrus SR22. It flew recently in Mojave with Dick Rutan at the controls.
SMA had their new 6 Cyl 460 (350-420 hp) in their booth. It is being tested now.
Deltahawk had an SR20 there with their updated engine, flown up from Florida. Looks good, but still no definative delivery dates for production engines.
Cessna had the SMA-powered 182 JT-A there, and also unvailed the diesel 172 JT-A, powered by Continental CD155 diesel (formerly Thielert).
Piper is offering a diesel option for the Archer, a Continental CD155.
Redbird had the Redhawk Diesel 172 in their booth, also powered by a CD155.
American Champion announced that the Denali Scout will be available with an Austro 180 hp diesel.
Glasair Aviation had two diesel Sportsman aircraft there, both with Continental CD155, both flown in, one (mine) from NV, and one from the factory in Arlington. I can tell you that the diesel is very economical and pleasant to fly.
Not at Oshkosh, but Wilksch Airmotive is finishing testing on their 170 hp 4 cyl engine, which may soon be available, along with their GII 125 hp 3 cyl. Their website www.wilksch.net
has been updated. it's worth a look. I've been flying my RV9 with G1 120 hp 3 cyl for almost 6 years, 500 hours with excellent results. IMO, this is the best hope for homebuilders who would like a diesel, as it is the simplest, lightest, and probably the lowest cost aerodiesel out there (hard knowing the cost, since they aren't offering it yet, but my 3 cyl was very reasonable, in line with equivalent Lyc).
That's all I can think of.
RV9-WAM 120 diesel, flying since 2008, 495 hours.
Glasair Sportsman - Continental CD155 diesel, flying since June, 50 hours.
RV10 -Airframe complete, waiting for suitable diesel!