Almost all of the best Java developers that I know (including many who ran Java user groups, podcasts, started well known projects) would choose to use Scala on a new project rather than Java. Given Scala's present state (many performance problems were ironed out in 2.8.0), I simply don't see a single reason not to do so.
It's quite puzzling why the author of the parent article lumps it in with Ruby as the two aren't very similar.
On the other hand, I've seen a friend who's a good (but not great - and he's well aware of it) developer, but is rather entrepreneurial (quit a very well paying job to work on his own project with no external funding) was very surprised after I told him Scala is statically typed. Apparently Java developers almost develop a sort of a Stockholm syndrome that leads them to believe that "if it isn't verbose and limiting, it must be dynamically typed and slow".
But you are forgetting that its much easier to hire experienced Java programmers than experienced Scala programmers, simply because there are not that many of the latter.
If a Java, C#, C++ (or F# or OCaml) programmer isn't able to pick up Scala (or any other typed object oriented language) quickly on the job, they aren't that great of a programmer (even if they are experienced).
Same for knowing any of {Perl, Python, Ruby} and being able to easily pick up the other. Some of the more advanced idioms may take longer to learn, but it's a fact of life that you'll have to learn new languages as you go.
On the other hand, if you need to hire average but experienced programmers (e.g., if you're doing outsourced CRUD app development) then you might have an argument.
> I dont want to pay people to 'pick things up on the job'.
Google would disagree. As would Microsoft (they were very interested in interviewing me, even though I've never done Windows or C# programming and made that clear on my resume), Facebook, Amazon (http://groups.google.com/group/mi.jobs/msg/d81b6c1fa8f361fc) and other serious software successes.
Sounds like you want coders, not developers. What reason would talented developers (the ones with offers from all of the above, plus start-ups competing with you) to join you?
It's quite puzzling why the author of the parent article lumps it in with Ruby as the two aren't very similar.
On the other hand, I've seen a friend who's a good (but not great - and he's well aware of it) developer, but is rather entrepreneurial (quit a very well paying job to work on his own project with no external funding) was very surprised after I told him Scala is statically typed. Apparently Java developers almost develop a sort of a Stockholm syndrome that leads them to believe that "if it isn't verbose and limiting, it must be dynamically typed and slow".