Actually, though I'm using 2.X in everything I'm doing, I'd rather see it only appear in 3.X. There has to be something that drives people to port stuff to 3.X or it's not going to happen. Dramatic speed improvements such as what this potentially provides would be extremely helpful in that regard. The other hope right now, is of course unladen swallow, which hasn't proved to be very significant yet, as far as I'm concerned.
3.X can be pretty awesome, but as long as projects want to maintain compatibility with 2.5 or earlier, it's going to be difficult to get some serious porting momentum going. Once 2.6+ becomes a practical development target, 3.x will be a much easier sell.
At least, that's my perspective after watching PHP 5 slowly catch on amongst PHPers, even though it had many more improvements (e.g. objects are no longer value types), and far fewer compatibility breaks.
People are lazy. I still hear people wanting Perl 5.8 compatibility for my modules, even though 5.10 is 2 years old and has 100% backwards and forwards compatibility with Perl 5.8. In other words, all your existing code will run unmodified, and any 5.10-specific features you use will cause 5.8 to die at compile time.
I use a lot of Perl 5.8 at the LoC because it's the only dynamic language that comes installed by default on Solaris 10. That, and because it is the primary language of a proprietary product that we have to use. I'd love to use Perl 5.10, but then I'd have to install it on all of the machines on which my code is expected to run. If I had that kind of control, I'd skip Perl and go straight to Python or Ruby. (Actually, that was a lie, I'd use Common Lisp if I could.) As it is, I've standardized on Perl 5.8.
The product I am talking about is Signiant:http://www.signiant.com/.
It's a file based workflow application that basically that is written in Perl in the same sense that emacs is written in emacs lisp. The idea is for people to write workflows in the embedded Perl environment which is the same across of the machines on which Signiant is installed. I could use another interpretor, but that would require extra work and I wouldn't be able to use a lot of the Signiant specific code.
