AT&T has announced new data plans for smartphone and tablet customers that will affect both iPhone and iPad users. The new smartphone data plans include AT&T Data Plus 300MB, which includes 300MB of monthly data for $20, AT&T Data Pro 3GB, which offers 3GB for $30, and AT&T Data Pro 5GB, which offers 5GB for $50 and also includes mobile hotspot tethering. Customers on the latter two plans can pay $10 per additional gigabyte, while…
