I'm no lawyer, but my guess is that Sony currently don't see EQEmu as a threat to their revenue and it is not in their interest (financially) to test the legality of it in a court of law. If they saw their player base declining and thousands of people playing on public EQEmu servers, they may think differently. Also, if anyone was benefitting financially from the Emu, that may attract the attention of the lawyers as well.

EDIT: Search google with the keywords 'emulator law precedent'

http://www.google.com/search?sourcei...+law+precedent

I only scanned the first few hits, but it seems a pretty grey area

EDIT2: You may have seen it already, but there is a post in the FAQ forum by Hogie titled 'What do Sony think about this project'

http://www.eqemulator.net/forums/viewtopic.php?t=9018