I just wanted to mention that LG seems to have made some big steps forward with MKV Support in their new products. My new TV streams MKVs with MPEG2 video perfectly, it can stream very high rate video in MPEG4 (Eg. Avatar) without issue too.
A couple of small bugs remain such as stutters in some VC-1 files and no support for DD5.1 core extraction from TrueHD but overall the LG interface is good and the vast majority of HD and SD rips play perfectly.