It's too long to post, so I'll just steal SDN's shortened version:
Q: Why do some things appear different in the new Star Trek movie?
A: There is an alternative timeline created by Nero traveling back in time.
Q: Is everything different in the alternative timeline?
A: No, some things remain the same.
Q: Does this alternative timeline wipe out the original timeline (from TOS -Nemesis)?
A: No, quantum theory says they both co-exist.
Q: Does the original timeline continue?
A: Yes, again as explained by quantum theory.
Q: Does this quantum theory approach conform to 'Trek science?'
A: Depends on the episode, but it is explicitly cited by Data in the episode "Parallels.
Good. I like that they've at least put enough thought into it to say "yeah, we know it's different, and here's a reason." My hopes have just raised a tad.