We were promised that the phone-that-goes-tablet would ship in April, and it looks like ASUS is keeping its word. The PadFone and its corresponding tablet shell and keyboard dock, will be up for pre-order in Taiwan starting tomorrow, going on sale April 20th. On its own, the Snapdragon S4-powered 1.5GHz dual-core phone is priced at NT$17,990 (US$610), while the tablet set -- including that curious Bluetooth headset / stylus -- will set you back NT$24,980 (around US$850). If you're thinking keyboard add-ons are