If you’ve built a third-party application for Twitter, you’ll want to think carefully about what you call it, following the company trademarking the term ‘Tweet’.

The official response has been posted on the Twitter blog by Biz Stone, after Robin Wauters highlighted the issue over at Techcrunch. The official announcement is:

‘We have applied to trademark Tweet because it is clearly attached to Twitter from a brand perspective but we have no intention of “going after” the wonderful applications and services that use the word in their name when associated with Twitter. In fact, we encourage the use of the word Tweet. However, if we come across a confusing or damaging project, the recourse to act responsibly to protect both users and our brand is important.

Regarding the use of the word Twitter in projects, we are a bit more wary although there are some exceptions here as well. After all, Twitter is the name of our service and our company so the potential for confusion is much higher. When folks ask us about naming their application with “Twitter” we generally respond by suggesting more original branding for their project. This avoids potential confusion down the line.’

Which is interesting from a marketing point of view – Twitter has namechecked and praised some of the great apps currently using the word ‘Tweet’, including Tweetdeck for example, and suggests it may only use the trademark to go other apps which try to pass themselves of as official, for example.

Then again, ‘to tweet’ or ‘I’ve just tweeted’ suggests common usage of the word as a verb anyway. I’d be interested in hearing from any legal experts about what that would mean for any trademark cases.

And Mark Evans points out that Tweet.com is currently a site claiming to be about birds.

So if you can’t use ‘Twitter’, and might want to stay away from ‘Tweet’, what about Twit?

Well, that could cause problems as well – Robert Scoble reports that Leo LaPorte has trademarked ‘Twit’ for his longrunning TWiT TV netcast network (It stands for This Week in Tech if you didn’t know, rather than being Twitter related, and is something I recommend having a listen to…). There’s a related Friendfeed discussion going on…

So you might want to steer clear of Twitter, Tweet and Twit.

There are obviously reasons why Twitter wants to maintain some clarity between company products and 3rd party applications – particularly when they might be launching more of their own for premium users. At the same time, the constant referrals to ‘Tweet’ and ‘Twit’ have definitely helped publicity and common usage of the parent service, as has the availability of such services.

At the same time, the generic terms aren’t as well used – for instance, microblogging. Which is a bit of a shame, given 140char’s ranking for the term ‘microblogging blog‘!

Personally, I’d recommend building your own brand name – it’s a long term win but means you aren’t tied to one service or risking trademark problems. The short term benefit of going for the most common Twitter terms is likely to be waning as so many exist, and you’ll be able to carve out your own niche.