It works almost identically to the Instapaper bookmarklet – just click on the icon and the extension will save the active tab to your ‘Read Later’ account. Then, whenever you access the service with the same login, you’ll find that the article or link has already been added to your account.
Furthermore, on specific sites such as Reddit, HackerNews and Digg, you should also see a dedicated ‘Instapaper’ link next to listed articles.
Brian Donohue of Betaworks says the firm has “a ton of other great features” planned for Instapaper’s browser extensions and will be rolling them out to users over the coming months. Maybe that Safari extension referenced last month?