For the easiest way to check and see which titles have what, use this excellently put together site:
http://www.blu-raystats.com/stats.php
You can sort by audio and see all the PCM titles, 24-bit PCM titles, dts-ma 5.1, 6.1, 7.1, etc., etc., etc.
To summarize, currently 66% of all Blu-ray Disc titles on the market feature lossless audio.
Code:
LPCM 203 40%
dts-ma 78 15%
TrueHD 56 11%