And since not everyone is in the UK, I shall direct you to this:
http://www.copyright.gov/help/faq/faq-general.html#what
So while its within their rights to get pissy with their mods, if someone DID want to bring a lawsuit to bear on someone for a minecraft mod (In the U.S. at least) you'd not only have to pay for copyright registration, you'd also have to serve whoever you think is breaching your copyright. You'd also have to show that somehow this person has caused damages. This could prove to be difficult to do considering Technic doesn't claim the mods are theirs, we don't 'steal' anything and we gladly donate and tell others to donate. The mods themselves aren't being sold either. We also don't accept donations at all and instead direct them to the modders themselves.
Last I heard the IC2 team has had over 1k in donations to them since being inculded in Technic. Exposure is a good thing.