It's anyone's guess when the next version might be released. Since you mention D11, you should only buy a copy of D11.5 if you need it, for example to publish to the latest Macs. Otherwise, I can't see any reason to not wait until D12 is released.
Answer depends (as Sean suggested) on what you need to do.
Do you have a version of Director already? If so, what version?
Director 11.5 is the current version. Adobe have been demoing new enahancements to Director (which is guessed to be D12 or whatever it will be called) at various conferences this year. Release dates are never indicated but if you use a bit of educated guesswork, it would be expected that something be annouced within the next 6 months. I say that as the last demo was just recently (Casual Connect). The first demo was at GDC (March I think). So, you'd hope that there would be a release within a year of the first demo. But, that's just a lot of assumptions:)
Thanks Sean, that's what I thought.
I'm using Director 6.5 and reworking some old projects.
I'll stick with that for now. The projectors fine under 'XP Home' and that's all I need for the moment.
If you only work wit XP, i suggest to buy a licence of MX2004 ( Dir 10 )on ebay or similar sources.
Maybe Adobe will offer an upgrade to Director 12 in the future ( 2030 or so)
Should be around 250$