I dont think any of the Android clients use the Instapaper API (http://www.instapaper.com/api/full http://www.instapaper.com/api/full) - they scrape the website

I dont think any of the Android clients use the Instapaper API (http://www.instapaper.com/api/full http://www.instapaper.com/api/full) - they scrape the website, making it impossible to do things like sync reading postion across devices. There is a decent Window Phone 7 client that uses the API - Stacks for Instapaper (http://www.stacksforinstapaper.com/ http://www.stacksforinstapaper.com/) and one for HP/Palm webOS - Paper Mache (http://ryanwatkins.net/software/papermache/ http://ryanwatkins.net/software/papermache/ - disclosure, its my app) Interestingly the Terms of the Instapaper API prevent any integration with other "Read Later" apps, though Read It Later API terms do not seems to have this restriction. "Apps must not include support for any other services that compete with or are substantially similar to Instapaper, unless the app uses only the “Add Bookmark” and/or “Verify Credentials” methods from this API. Instapaper reserves the right to decide whether another service or application is considered a competitor or substantially similar." (http://www.instapaper.com/api/terms http://www.instapaper.com/api/terms)