RIM is hard at work developing their own Twitter client for the BlackBerry, according to numerous reports across the social media blogosphere.

Though plenty of apps already exist (SocialScope, Tweetcaster, TwitterBerry, UberTwitter), this would be the first official Twitter client for BlackBerry.

The application would most likely take advantage of full integration into the rest of the phone, making for a nice laundry list of included features. For example, the app will automatically be connected to a user’s address book, browser, and device setup wizard. CrackBerry says that the actual user interface of the application will likely match those of RIM designs for its other social networking apps.

A Twitter app, RIM’s client will be expected to include most, if not all, of the features of its rivals-to-be. Basically, if there’s some action you can take on Twitter’s Web site, there’s really nothing stopping developers from implementing said action into a mobile app.

When the client is finally released, it will be yet another testament to the fact that Twitter is now one of the most popular and powerful social networking sites on the Web.

As if Twitter needed RIM’s recognition.

On Friday, the young company confirmed the closing of a $100 million round of funding with new and previous investors after a couple weeks’ worth of swirling speculation. The investors—Insight Venture Partners, T. Rowe Price, Institutional Venture Partners, Spark Capital, Benchmark Capital, and Morgan Stanley—are said to value at Twitter at $1 billion.

While Twitter will be expected to expand, evolve, and improve its site over the quarters to come, Twitter-based clients will need to follow in tandem to ensure that they still fulfill all the capabilities of the original site. If RIM’s app has this taken care of, BlackBerry users won’t need to turn to third-party apps anymore.