Twistory, which lets people save their tweet backlog to their favorite calendaring application, has finally come through with full support for popular Web-based calendaring service Google Calendar.

You can now subscribe to Twistory using your existing Twitter account and automatically view in Google Calendar when you’ve tweeted what. Up until now, compatibility with Google Calendar was a little flaky, but the team behind Twistory tells me it is now finally stable.

Twistory is available for free, allowing you to visualize your last month worth of tweets in your calendaring application of choice.

There’s also a paid version, Twistory Pro ($1/month), which gives you access to your entire Twitter backlog (currently limited by Twitter to 3,200 tweets) and allows you to export your entire Twitter history as a CSV file.

Ever tried to look up that hilariously funny, wicked smart or straight up historic message you tweeted at that birthday party about three weeks ago? Yeah, good luck finding it if you’re not using a tool like Twistory.

As we wrote when we first featured the app nearly three years ago, the app lets you subscribe to (public) messages from any Twitter user, including your own, in any popular desktop or online calendaring application (iCal, Google Calendar, etc.).

The app has amassed over 40,000 users by now, creator Tijs Vrolix tells me, and he felt it was time for an upgrade.

The update is now complete, bringing better performance and better stability to the tool. Try it: once you authorize Twistory to access your tweets, you’ll see tweets for the past 30 days appear on the appropriate date and time in your favorite calendar application, within seconds.

In the interest of making some money, Twistory now also boasts a premium version. For $1 a month, that Pro version of the tool lets you export your entire Twitter backlog as a CSV file, which Vrolix says was probably the most often user-requested feature.

Note that the backlog is limited to 3,200 tweets due to Twitter-imposed API limitations.

Next on the roadmap: support for retweets.

It’s a very simple tool, built by Tijs Vrolix to show off his coding and design skills: Subscribe to messages from any Twitter user in any popular desktop or online calendaring application (iCal, Google Calendar, etc.). Those messages are then automatically added to the calendar, at the appropriate day and time.

Useful? I don’t know. It’s certainly useful to closely monitor/stalk people (or yourself). If you want to add my daily words of wisdom to your calendar, my page is here (which also includes a graph of total twitter usage by day.

Thanks to Robin Wauters for the tip.