One word that’s getting mentioned a lot by many Twitter users these days is TweetDeck, the desktop application for interacting with your Twitter community that’s the preferred app by increasing numbers of people including me.

And one individual who’s getting a lot of attention at the moment is Iain Dodsworth, the London-based developer of TweetDeck, who I had the pleasure of meeting at the Social Media Cafe / Tuttle Club get-together in London on Friday morning.

It’s not often I get the opportunity for a casual face-to-face chat with the developer of a computer program that I use and find very useful, so it was a pleasure for me to have that opportunity.

We had a most interesting conversation that embraced a wide range of topics, some out-loud thinking as well as specific ideas on what might be coming in TweetDeck, including support for multiple accounts, filtering the Twitter content stream, colour highlighting of contacts, a sort of directory of contacts (especially useful if you use TweetDeck on multiple devices), importing and exporting your contacts, a version of TweetDeck for the iPhone, and more.

We also had a bit of a laugh about my recent obsession with seeing my own sent Twitter direct messages within TweetDeck, which you couldn’t do until Iain added that functionality in the latest beta he released just before Christmas. That’s what I call a developer who really does listen to his users!

Christian Payne (aka Documentally) recorded a video conversation with Iain on Friday during which he talked about his plans for TweetDeck including enhancements and planned TweetDeck Pro. It’s a good interview, worth watching.

Lloyd Davis, the man behind the Tuttle Club, also chatted with Iain as part of a podcast Lloyd recorded on Friday morning; you can hear that segment towards the end of the 15-minute audio.

So Iain’s got a lot going for him at the moment: a great app, a willingness to listen to and engage with his users around the world, those users who want him to succeed with TweetDeck and how it evolves, all of which rides on the wave of increasing interest in Twitter out on the edge of the mainstream as more and more people sign up and contribute to Twitter’s explosive growth.

The precarious nature of Twitter aside – a business started as a side project, with still no discernable business model and which could all stop tomorrow – there are currently well over 500 third-party applications and services created to work in some way with Twitter, adding functionality and utility to the overall user experience.

In other words, it’s a crowded marketplace out there for an application developer, especially with an app that is free (hearing more about TweetDeck Pro and TweetDeck in the enterprise will be interesting: paid-for versions with additional functionality?) and very popular, so you have to have more than just your app to be on that potential success trajectory.

With a developer like Iain Dodsworth, it’s clear that TweetDeck is indeed more than just the app. I guess the main question is how much and how far can just one man go with an app that works on the three primary computing platforms – Windows, Apple and Linux – and where all the indicators are that its popularity and demand will only increase?

That question is for the next stage in TweetDeck’s evolution, one that’s bound up with Twitter’s, too. Meanwhile, if you’re a Twitter user, check out TweetDeck today.