Google Wave, Google's answer to the question "What if email was invited in 2009?", makes it's first wide-audience debut tomorrow to approximately 100,000 people.

Google clarified things earlier today with an update to their blog. They specifically highlighted the four key ways you can secure an invite. Here are the methods and what you need to know:

1. You signed up early on for a Google Wave account. Google put up a request form for Wave invites not long after Wave was announced. Most of the invites arriving tomorrow will go to people on that list. Your chances improve if you signed up early on and wrote a message to the Wave team.

2. You have an account on the Developer Preview of Wave. The Sandbox version of Google Wave has been active for a select group of developers for several months now, allowing them to test Wave, report bugs, and build Wave extensions. They will all get accounts.

3. Some paying users of Google Apps will get accounts. It’s likely several companies asked Google for invites when the real-time tool launched. They will get accounts. Some schools that use Google Apps will also get early access.

4. You are invited by someone currently using Wave. This is the most intriguing revelation made today by the search giant. Here’s how Google explained it:

“We’ll ask some of these early users to nominate people they know also to receive early invitations — Google Wave is a lot more useful if your friends, family and colleagues have it too. This, of course, will just be the beginning. If all goes well we will soon be inviting many more to try out Google Wave.”

I'm extremely excited and extremely hopeful I signed up earlier enough for an invite to make it in the first 100k.