Let me start of by saying that I don't even know if this is an issue with Linguistics itself, but it only happens to me when I use this gem, so I figured I should report it just in case.
The issue can be fixed by adding
if RUBY_VERSION =~ /1.9/ Encoding.default_external = Encoding::UTF_8 Encoding.default_internal = Encoding::UTF_8 end
to the top of your Gemfile. If I don't add that I get "invalid byte sequence in US-ASCII" when trying to use Linguistics in my web apps. This was also the case for the old 1.0.9 version. It happens with both Ruby 1.9 and 2.0.