This thread on the scala-debate mailing list (originally from scala-user) should prove an interesting discussion. It basically covers the two key elements for language adoption in the Java mindshare space: Tool support and stable backing.

Erik Engbrecht makes the good point that tool support is coming along and the people working on Scala are paid to do so.

The tool support is definitely still in active development. There's a general feature race going on between the big three IDEs (Eclipse, NetBeans and IDEA) to support as many languages as possible. With all it's static analysis, Scala has a lot of potential for IDE support. The key, however, is going to be getting past Java's support. All the extra overhead static typing and analysis brings to the table requires the IDE to handle a lot of things developers can otherwise ignore with dynamic languages. For Scala to compete with Java, it's going to need to equal Java on the stuff that's similar, and provide a better view for developers on all the implicit stuff.

I don't think a bunch of researchers working on the language is quite as solid an endorsement as corporate investment, but that doesn't mean it's not worth a lot. For a lot of people it's going to stand up better as an argument than "the BDFL will not abandon this language, because it's his baby."