No 64-bit version is a big disappointment for a plugin coming out this long after CS4 release.
I don't know what previous betas were like, but I tried opening an 86 megapixel pano with B4 and it took so long I thought Photoshop had hung (I didn't use a stopwatch, but I'd guess at least 5 minutes). So hopefully there's still some room for improvement.
The actual results looked decent though, I'll have to try some more images. Definitely one of those tools where a little goes a long way though.