Instapaper should be on Android. Its parsing can also get better, Apple's Reader feature does a better job at grabbing the whole article and just the article (with Instapaper I usually need to first find a print this article link).
It could also become a good way to find new content as Instapaper knows what's being saved and should also know what's really being read.
For Android you should try Instafetch. Besides all the known features from Instapaper, he uses his own server to parse the articles. The nice thing about this is that he uses Readability's algorithm to parse them, which results in really nice layout.
The advantage of the same app on all the platforms is I don't have to worry about where I added it if I want to read on my Android phone, iPad, or Kindle. If I read it on my phone it should be marked read on the iPad. If I leave off halfway though that should be reflected. Etc etc.
Instafetch works with Instapaper's list of articles, so no matter where you add a link (or mark as read), it will be synced with all devices including Android/Instafetch.
Didn't have the chance to test if it remembers where you left reading across devices though.
Anyway, I understand the benefit of having the app from the same provider. My point was that if you need a solution now, you can have it.
It could also become a good way to find new content as Instapaper knows what's being saved and should also know what's really being read.