I don't really understand why they need to limit the number of beta testers - I think it was said that only about 1000 users will get access to the beta client.
Because it's probably going to fail to cope with all the weird and wonderful Linux installations out there to start with & they'd rather it didn't gain a reputation as being a buggy sack of offal.
It's hardly unusual for companies to have a limited beta before they open out to a wider audience.
