Finally, Google Apps users now can have the full access to Google+ service. Previously, if you’re using Google App for your domain, you need to migrate to other Google account to get the service. I did that already. But now, Google made it available for Google Apps user.
Quoting from Google Enterprise blog:

Starting now you can manually turn on Google+ for your organization. Once Google+ is turned on, your users will just need to sign up at google.com/+ to get started. For customers who use Google Apps for Business or the free version of Google Apps and who have chosen to automatically enable new services, Google+ will automatically become available to all of your users over the next several days.*
Google Apps users will have access to the same set of features that are available to every Google+ user, and more. In addition to sharing publicly or with your circles, you’ll also have the option to share with everyone in your organization, even if you haven’t added all of those people to a circle.

I don’t use Google+ on daily basis. And since I’m already linked my other Google account to Google+, I am not sure what I need to do with my current Google Apps account. Here are some screenshots about the registration/activation processes.
If you’re already logging in to your Google Apps account from your internet browser — opening an email for example — you can directly go to plus.google.com or google.com/+

Since Google+ needs Picasa Web Albums for photo sharing and Google Talk for chat, you need to link it to you existing Picasa Web Albums.


Next, you will be prompted to add people to your circles. Google+ already has some suggestions. You can skip this step if you want.

Google+ thinks that you want to follow public posts from interesting and famous people, including celebrities. If you don’t want to follow them, just skip to next page.

Since I didn’t add anyone into my circles, I’m considered as “lonely”. :)

And, my Google+ page with Google Apps service is ready. I currently keep this account (under Google Apps) inactive for now by not adding people to my circles. I will go with my other account that already running.