Note that Nullriver stated, +"Looks like Apple has decided they will not be allowing any tethering applications in the AppStore. As such, NetShare will not be available in the iTunes AppStore."+
The fact that no one
else can purchase NetShare at this point says nothing about the functionality of the app for users that
already purchased it. Certainly, there will be no updates. But, if the app works at this point (and reportedly, it does, through the 2.02 and 2.1 updates), then it works. Not sure what basis you would have for requesting a refund under those circumstances. If a subsequent update 'breaks' the app, then a refund could be requested.
The refund would need to be issued by Apple, using the Report a Problem link from the Purchase History of the iTunes Store account used to purchase the app. One blogger who purchased the app directly on the iPhone, then was unable to transfer it to iTunes since it was subsequently pulled from the App Store, did report getting a refund from Apple. Faethor, apps are DRM-protected and linked to the iTunes Store account used to purchase them. Same account, the app works. Different account, it doesn't, and it gets deleted from the iPhone.