I'm really happy to see this happening, and hope this represents a step in publicizing our apps more on the sites in general. I evangelize the Wikipedia app to everyone I know :)
Are there plans to test the location of the app on the page and see where drives most engagement? I'd be interested to see if higher placement allowed for more app conversions, but we'd need data available to tell us if the user actually continues their search after download, either in the app or on the portal page.