Turbine href="http://www.lotro.com/news/pressreleases/1334-the-lord-of-the-rings-online-rise-of-isengard-to-launch-beta-program-on-july-27th">Announced
today that initial Beta testing for the Rise
of Isengard, the next expansion for href="http://www.tentonhammer.com/lotro">the Lord
of the Rings Online, will begin on July
27. 

The Rise of Isengard Beta Program is Invite-only.
Players
across North America and Europe can pre-purchase Rise of Isengard to
receive special benefits including preferred access to the Beta Program.

Testing runs through 3 stages:

1. Palantir program - Invitation-only, first wave of bug
   detection . Invitations are sent "randomly" to players of all account
   levels (VIP, Premium, F2P), but pre-ordering means you get preferred
   status and are more likely to get the nod. Participants must agree to a
   Non-Disclosure Agreement (NDA). This is what's happening next
   week. 
2. Bullroarer closed Beta - Apply for this on LotRO forums.
   Second wave of bug-finding. NDA still holds. This will likely happen in
   August.
3. Bullroarer open Beta - Anyone can download the Bullroarer
   client and get a preview. Final wave of bug-finding before it goes
   live. Probably coming in September a few weeks before launch.

So how do you get invited? Wait patiently and it might show up
in your email. According to Lead Community Specialist
Sapience: 

All players with an active account (that means Free, Premium,
and VIP/Lifetime who are actively playing the game) have a chance to be
invited to Beta. If you have pre-ordered Rise of Isengard, then you
have a better chance.
I do wish to be clear; there is no way to guarantee an invitation.
Also, we will be inviting more people through the course of the Beta,
so just because you aren't invited in the first round of invites
doesn't mean you won't be invited at all. You may be invited later in
the process.

And if you do get invited, remember the first 2 Fight Club
rules. According to the LotRO
Twitter feed:

Reminder: Beta is covered by NDA. Even stating that
you were
invited is a violation and can cause your invitation to be revoked.

Keep your fingers crossed and an eye on your inbox.