Is it safe to update manually or can it ruin your phone?
If you are referring to that update to 2.1(the version that is in the droid hacks forum) then that takes much more effort and knowledge. You would need to root your phone first and then follow several steps to get this done. Completely different then the first update I listed. This being said, if you follow the steps correctly and have a back up copy you are probably ok. Just be aware that doing this type of update could brick your phone if not done correctly.
If they do it that way however it will only go out to about a thousand people initially. Then they increased it each day, adding more people. They may take 2 days off and then started releasing to everybody.
All speculation of course. I'm hopeful.