This is a really awesome music player for iOS by +Adam Bell , and yes it scrobbles! To enable scrobbling, long-press on the album art, and then tap the cog icon at the bottom right, then login with your Last.fm account.
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App Store – Reprise
Read reviews, get customer ratings, see screenshots, and learn more about Reprise on the App Store. Download Reprise and enjoy it on your iPhone, iPad, and iPod touch.