So far I have only seen designs based on micro and nanoBTX, which again goes to show that the uptake has been very slow. However, as a small form factor platform BTX is actually looking increasingly interesting. Considering that the biggest problem in a SFF system is heat dissipation, hopefully BTX will allow for overall improved system designs. Shuttle was the first company to bring such a product to market with the SB86i but it wasn't a huge hit.
Read on over at Trusted Reviews.