I literally cannot believe I am seeing this thread. It just blew my mind. I kept reading and reading thinking someone was going to set the original poster straight, and it never happened!
This brings back ugly memories of deja vu from the whole Mac OS X 10.0 (4K78) fiasco.
I'm going to say this once, and once only: there is only one build of Mac OS X 10.1, and it's build 5G64. There are no newer builds. Not even for a potential update to 10.1. There is no 5G68, and never was. There is no 5G70. There are no builds beyond 5G64, anywhere, and you can take that to the bank. There are also not multiple 5G64's. There's one and one only, and there's no difference whatsoever between what was given out at Seybold, what ADC got online, what ADC will get in the mail, and what you'll get if you get the official CD from Apple. It's all 5G64, and it's all the same. I don't know how much more simply or explicity to put it.
The whole purpose of build numbers is to have a unique identifier for a build, for a multitude of reasons. It would not make any sense to have different versions of the same build; that defeats the very purpose of a build number. If ANYTHING changes, by very definition, it has to be a new build. It's as simple as that. Also, Apple had multiple GM candidates before arriving at the final GM candidate that was accepted as GM (5G64). There were no builds run after this, and none were ever started. There was never even a 5G65. You can believe what you want, but it's the truth.
Back with the whole 4K78 deal, a lot of people wouldn't believe that the shipping 10.0 was 4K78. They swore up and down that there MUST be newer builds; their friend/neighbor/dog had SEEN them...in fact they must be in the 4K90's by now! But, alas, it was 4K78. When it became clearer and clearer that 4K78 was 10.0 GM, people couldn't take it. They said, "Maybe Steve has a secret stash of the real 10.0!" But then when it shipped on March 24, and they got their own hands on it and installed it, they still couldn't believe it. They saw 4K78 in the about box, and didn't know what to do. So they started making stuff up. Things like "there must be multiple 4K78's...maybe even dozens" or "well the developer 4K78 has all the debug code in it, and the real 4K78 is recompiled to make it super-lucky fast". Unfortunately, that's all wrong. The developer 4K78 and the retail 4K78 were identical. Byte for byte. Bit for bit. In every way. We even ran checksums on them, including md5 (a checksum for comparison of files with no known way of defeating it). Identical. People still wouldn't believe it. To this day, there's still some people who believe that the retail 4K78 is somehow faster. Well, I guess they can think whatever they want, if it makes them feel better.
So if it makes you feel better to think there's multiple 5G64's, or that there's secret builds out there (like 5G68 and other things that don't exist and never have), feel free. Just as long as you don't mind being completely, totally, 100% wrong.
So...one more time:
There is only one 5G64*
There are no builds higher than 5G64, anywhere**
No one has build 5G68
* Note: there *are* two different versions of the 5G64 CD: an updater and a full install. The update CD checks if you have a previous X installation and the full install will be in the retail box and with machines. But there's still no difference between the builds of 5G64. It's a unique identifier that will never change.
** Note 2: Before anyone says "well that's rediculous...maybe 5G64 is 10.1 like you say, but certainly there's builds newer than 5G64!" Nope. Not right now. In the build series which culminated in 5G64 (10.1 GM), there are no newer builds. And everyone who worked feverishly on it at Apple is taking a well-deserved break.
