Hi Caroline,
Hhm, no Inkscape doesn't have an automatic update feature, or any notification system built into it. You can keep up with current versions by visiting the Inkscape website (inkscape.org). In the upper right corner of the window, the current stable version is shown with a download link. Plus the homepage contains the most current news, and will always have a notation (or short article) about upcoming new releases.
Inkscape is an open source project, and is constantly under development. Because of this, you can get the very most current version (often, if not always, updated daily) from this page:
http://inkscape.org/download/?lang=en.
Always here at InkscapeForum, there will be some discussion of upcoming version upgrades, or recent upgrades. Although granted you would have to look for it.
Also on the Inkscape website, in the navigation menu on the left side of the page, under Development, there's a link called Roadmap (
http://wiki.inkscape.org/wiki/index.php/Roadmap). There you can find very rough estimates of the next few version upgrades, as well as learn about various features planned to be included with them. They are very rough estimates though, and you should keep an eye either on the News on the homepage, or here at InkscapeForum, for more accurrate estimates.