This is in preparation for a load test that will be taking place tonight. Another larger expansion will be taking place next Thursday, as well as another load test. Version 1.00 is definitely an improvement over previous iterations (having the service full of people definitely makes a difference), with Sony firmly stressing that this is the beginning of the journey, with plenty more updates and additions to come.
Update: The beta will expand in the US as well, as a ton of new invites are being sent to American PS3 users. Please join us on Home when you get a chance!
Update 2: Looks like an e-mail snafu has delayed the European beta expansion. Thousands of e-mails that are awaiting eager users are caught somewhere in the interwebs -- which means our European readers won't be able to get new Home invites for at least a few more days. Sorry. Read more here. [Thanks, brampf!]