From what another GSP said (think it was Gameservers) was they the 3 that have got pre-order rental prices already out have been give a leg up (preferential treatment it seems) to get ahead of the competition. So I doubt it's an indication of the beta date as other GSP's have known for a while that they can't release pricing until then.
I also read, but can't find it now, that nobody will be able to rent servers for the beta, it'll purely from release day onwards only. So I suspect they'll be ending the beta before the release day.
Someone was spouting off earlier that they were a friend of an EA employee & was adamant that the beta would be released on 9th September. Personally, think it's a load of tosh & it'll come when it's ready.