Twitter has experienced some ups and downs over the last few weeks. The site has buckled under the strain of trying to absorb thousands of new users and the prolific tweeting of super users like Robert Scoble. Because of this, the site is frequently down or at least crippled so that you can only view the home page.

But Twitter has also broken new ground… on another planet. The Mars Phoenix lander is tweeting to a large group of ecstatic space-geeks (18,000 last I checked). Okay, so the tweets aren’t coming directly from Mars; there’s actually somebody at JPL (NASA’s Jet Propulsion Laboratory) typing for the lander. Veronica McGregor tweets in the Phoenix lander’s voice and even responds to questions in character.

But just as Twitter’s reach was extending beyond the planet a new terran threat has emerged. It’s called Plurk and it takes Twitter and adds a graphical timeline and more robust conversation capabilities. In Twitter, everything but direct messages are available for all to see, but in Plurk every plurk (or “tweet” if you prefer) is like it’s own chatroom, spawning side conversations that don’t muck up the main timeline with chatter. These conversations can be viewed on the timeline in a small popup window, or as their own individual page.

Plurk adds a few other things to the mix as well, such as a karma score. It’s clearly a gimmick to hook people, but it works on the obsessive-compulsive. It also encourages conversation and community because getting a good score requires talking to other people. Karma is not completely useless, though; a higher score unlocks features and little treats like extra emoticons. Plurk also boasts some file-sharing capabilities, like fellow Twitter-clone Pownce.

(Plurk has clearly raised the “strange name” bar. I shudder to think what people will assume a “plurker” is. To me “plurk” sounds like the noise a rock makes when you throw it in a lake. At least they’ve got their territory staked out on Google.)

So does Twitter have some real competition? It certainly looks like Plurk could ruffle some feathers over at Twitter HQ, but Twitter’s worst enemy seems to be their own popularity and the technological headache of scaling to accomodate so many users. That gives Plurk an opportunity to carve out a new niche and form an alternative community.

You can find my plurks at: http://www.plurk.com/user/vemrion