Since the news broke last night that Google has acquired Jaiku, every manner of opinion has surfaced on what it means, why they didn’t buy Twitter, who will, etc.

Never heard of Jaiku? It’s a micro-blogging tool. Or it’s a presence indicator. Or it’s an instant messaging application.

Here’s Jaiku’s own description:

Jaiku is an activity stream and presence sharing service that works from the Web and mobile phones. […] Jaiku is a way to connect with friends by sharing short messages called Jaikus. You can create your own stream of Jaikus and follow your friends.

In the ultimate compliment, here’s the description on Wikipedia:

Jaiku.com is a social networking and micro-blogging service comparable to Twitter.

So it might help to know what Twitter is:

Twitter is a community of friends and strangers from around the world sending updates about moments in their lives.  Friends near or far can use Twitter to remain somewhat close while far away. Curious people can make friends.  Bloggers can use it as a mini-blogging tool. Developers can use the API to make Twitter tools of their own. Possibilities are endless!

That makes sense and so it should be easy to understand what Jaiku is and how similar it and Twitter are.

With both, you can post your Tweets and Jaikus from the web using each service’s own interface (or choose from an increasing number of third-party applications and services: I use Twitku, for instance, where I can post to both at the same time); from an instant messaging program; and from a mobile phone.

I sometimes use Twitter from my phone when I’m away from a computer. Twitter makes it very easy and cheap with local numbers (in the US, UK and some other countries). Jaiku doesn’t – you have to SMS to a number in Finland. I wonder if that will quickly change under Google.

There’s one major difference between them both, though, and that is presence.

Jaiku includes the capability to show where you are at a given moment (think of Plazes to get an idea), something that many people find extremely useful, and which may provide one indicator of Google’s interest.

All this illustrates that it’s not easy to provide just a single definition of what a service like Jaiku is.

In essence, it’s what you want it to be.

I signed up for Jaiku earlier this year (Twitter last December). I use Twitter more as more of my friends are on this service than on Jaiku. Plus Twitter’s simplicity makes it far easier to use and to connect with others.

For me, both tools are a means to connect with other people in my circles of interest, with concise (140 characters or less) comments on whatever is on my mind however trivial to others such stream-of-thought commentary may appear.

In this sense, “micro-blogging” is probably an apt descriptor, as such 140-character commentary is akin to brief blog posts (and they get indexed by Google just as blog posts do). You can even display your micro-posts in your blog, as I do with Twitter here in the sidebar.

That’s how most people I know use Twitter and Jaiku, as this Jaiku screenshot indicates:

In any event, Jaiku has been snapped up by Google in a move that has lots of people speculating.

So why did Google buy Jaiku?

I think a good clue lies in the category under which Google’s official blog post about the deal has it categorized – mobile.

That makes sense to me, given Jaiku’s strong focus on mobile as well as Google’s.

So is it all about the mobile internet and presence? Think presence again and what Jaiku says you can do with Jaiku mobile:

Share your availability, location, and calendar

Imagine how that might integrate with some of the Google Apps.

Of all the media reporting and blog posts I’ve read, Chris Messina has the most intriguing conceptualization:

[…] In the scheme of things, it really doesn’t have anything to do with Twitter, other than that Twitter is a dumb network that happens to transport simple messages really well in a format like Jaiku’s while Jaiku is a mobile service that happens to send dumb messages around to demonstrate what social presence on the phone could look like. These services are actually night and day different and it’s no wonder that Google bought Jaiku and not Twitter.

[…] If anything, the nearest approximation to Jaiku is Plazes, which actually does the location-cum-presence thing and has mobile development experience.

Yes, I think it’s all about mobile and presence.