There are many now. The Panny 55 you mention has been very well rated in various reviews.
There's the Samsung BD-P2550 with HQV video processing (Reon VX chip). Note that DTS-HD MA was added through the firmware update v2.4; the units on store shelves may not come with support for it.
The Sony BDP-S550 also decodes these new codecs.
The high-end High-priced Denon DVD-3800BDCI ($2K).
The upcoming Oppo Digital BDP-83, which a lot of people are waiting for, myself included. ;-)
For an exhaustive list, you can check out the following website.
But be careful, there are some glaring errors on this list. When you see a blue box indicating internal decoding and it shows only 2.0 for analog outputs, it's a sure sign that there's no actual internal decoding of Dolby TrueHD or DTS-HD MA. Some errors for instance are the Sony BDP-S350, the Samsung BD-P1500 and the Panasonic DMP-BD35 (indicates 7.1 analog outs but it's an error as it only has 2.0).
Good luck! :-)