Read my reply to Mr flip.  The last crack down on private servers was to pick out servers making excess money for profit, and before anything was done blizzard had sent them several letters asking them to shut down. Like i said i ran a UO server for over 3 years and a WoW server for about 1 year and 3 months. That was for TERRA gaming, One issue which is possible, is a ban from the blizzard servers as you agree to their software terms.
  i would also like you to have a look at 
This. 
 first look at molten wow: 
 IN 
 12981 
 OUT 
 668229 <--- HOLY CRAP O.o 
 Now lets look at current players / Ques  
 Code:
 Players: 2912  Queue: 0  Players: 2425  Queue: 0  Uptime: 2 Days 2 Hours  Rates: Blizzlike x3  Players: 2599  Queue: 0  Players: 2767  Queue: 0  Players: 2627  Queue: 0  Players: 2712  Queue: 0  Players: 2082  Queue: 0
    And this is classed as quiet, usually ques of up to 900. 
 Ok back to top 100: 
 Now scroll right to the bottom of the page. 
 131184 Sites in our Database thats a hell of a lot of illegal activity dont you think? 
 And thats just the sites who enlisted on this particular voting site! 
 Many people think its illegal because of the Terms you sign, but a few paragraphs above the hosting section is the cheating section under the same section. If the same logic was applied, it would mean that cheating on world of Warcraft is a criminal offense, how silly? 
 The only time blizzard goes after a server is when they are: 
 1. Using blizzard source code for the server core ( Most Emulated server are written from bottom up by groups , not stolen, although i know a few games which use stolen cores, eg ragnarok ) 
 2. Redistribution of blizzard resources ( The client is freely available on the web, some people make 'custom' client files which is illegal ) 
 3. Make a profit ( 99% of servers shut down was for this reason , Wowscape made $500,000 per month!! ) 
 -Also i would like to note that the few servers that were targeted ( i think there were about 14 ) was just before Christmas, probably to boost sales. 
 Im pretty sure that we are at minimal risk of being shut down, especially running an outdated client as we cannot be attracting paying customers, so even if there was a legal issue, the bigger servers would go first.