The email I received from FoxFi said;
Users complaint not able to find FoxFi in Sprint or even do update that is how we found out. No there is no correspondence from Google. Carriers decide what app to show and what not, not Google. FoxFi has become too popular lately and attracts the attention of Sprint. Other less-popular tether apps will still show as long as they don't get too popular. So users always get the worse ones. I think the most popular tether app called PdaNet is also removed from the Sprint app store.
As of this post, Verizon, AT&T, and T-Mobile customers still have access to the popular tethering apps. If you are a Sprint customer however, you can click here to download FoxFi. Has this affected anyone?