Matt, cutural info on vietnamense is very sketchy--
wow--I'm getting more and more disappointed the more I research this; Jason's totally right--
I think my friends Le and Jay grew theirs as you would delenatii, but I have a few seedlings left here that I also bought from Antec; I assumed delenatii culture also for them but they're not responding well. Only the largest in the flask have survived (Antec ships flasks that aren't really flasks-- the plants are still in agar, but they transfer them en masse into those clear plastic hamburger containers before they ship) and I think they were deflasked way before the plants were ready. Combine that with culture that may very well not be correct and, well, that's my situation. I think most people are using best guesses at this point.
I'm also assuming by my difficulty with these that what I've got really is vietnamense. Supposedly Antec was the only nursery that was given the legal go-ahead to sell these, but hell, who knows. The fact that my friends brought theirs from flask to bloom in such a short time (everyone else I've talked to about these is having difficulty similar to mine, citing an incredibly slow-growing nature) points even more to the likelihood that the flask my friends got was Ho Chih Minh and not vietnamense. My delenatii seedlings deflasked at the same time have become giants by comparison.
The really sucky part for me is that you should have read the pride in the tone of Le and Jay's email when they sent the pic--quite an accomplishment had it really been vietnamense--and their disappointment (and initial disbelief, I would imagine) is going to be equally as great, as was mine when I first read Jason's post.
Major, major bummer.
Kev, I can't find any online listings anywhere for vietnamense in bud, and I would imagine (especially now) that one of such plants would run into the several hundreds of dollars, at least. Hybridizers pay small fortunes for breeding stock, especially when plants first become available.