To be fair to Pocket it would be better to say Instapaper is a simile of it, as Read-It-Later (Pocket's original name) was first.
edit: Read-It-Later was a web service initially. The idea behind it is the same as Instapaper. Instapaper released a mobile app before Read-It-Later (though Read-It-Later was around as early as 2007).
Please don't try to rewrite history. Instapaper was first and basically invented the space. The oldest comment in the iTunes reviews for Instapaper are from Aug 28, 2008 which is before the Android Market even existed. Read it Later originally launched in 2009.
Edit: Read-It-Later appears to have launched Apr 8, 2009.
Read-It-Later started as an article bookmarking system, and then pivoted to be like Instapaper (article parsing and delivery to a mobile app). Calling Read-It-Later older than Instapaper is like calling Bing older than Google. Bing is an evolution of msn search and Microsoft is older than Google.
Calling Instapaper a simile of Read-It-Later stikes me as misleading.
To call Bing older than Google seems entirely true to me (if nothing else, Bing is the heir to Yahoo search). Google was by no means the first search engine, and didn't transform the market or create one where there was previously none - they simply did it better than everyone else.
edit: Read-It-Later was a web service initially. The idea behind it is the same as Instapaper. Instapaper released a mobile app before Read-It-Later (though Read-It-Later was around as early as 2007).