Yes once you get in a Beta you are good for the next ones. You can always check by logging in on their site and when you click on your account you should see "Beta Access" on the right hand side under "MY PURCHASED GAMES"

Yeah I saw all that, and initially thought I would simply have continued access when they open the servers. Was just concerned because I assumed I would get a "We want to welcome you back for another weekend session!" email, but nothing yet. XP

Yeah I've been in every Beta and it took me a long time to get the email for this Beta. I'm sure you will get one soon and all it gives out is a code that you can give to your friends and you get a monkey pet if you participate in this Beta, but like I said it did take me longer than usual to get the email. I only got it like a few hours ago while lots of other members in my guild got it around noon EST.

Woke up this morning to my email. =)
Aw yee!