A lot of people (myself included) are convinced that Ruby is going to be the next major language (regardless of the platform it runs upon: native, JRuby, or the CLR). And, consequently, Ruby will have a major impact on enterprise development. In fact, I think that SOAR (SOA + Ruby) will be hugely popular in the coming years. As I've stated before, Ruby is the revenge of the Smalltalk crowd. It has a similar feel to developers but isn't hamstrung (like Smalltalk was) by proprietariness and expensive tools. Where Smalltalk failed, Ruby will succeed. Ruby is perfected positioned to become a major player in the SOA space: loose typing == flexibility, which is what SOA is all about.
Interestingly enough, if you look at the guys who were really into Java in 1995 and 1996, they are almost all heavily involved (and mostly billable now) in the Ruby world. Of course, this isn't an accurate barometer, but there is no good way to tell what is the Next Big Thing. Looking at people who've identified it before is as good a way as any.
Anticipating Ruby's move into the Enterprise world, next year features erubycon, the first Enterprise Ruby Conference. This is highly important to the Ruby community who wants to promote Ruby in the enterprise. Having a conference dedicated to this topic helps validate both Ruby's readiness for the enterprise and vice versa. I predict that, like RubyConf, this conference will be small this year, and in 5 years it'll be massive.