No, it's not an April Fool prank, as far as we're aware. Sprint and Verizon are taking pre-orders for the LG G5 starting today, and it will be officially available on April 1st. You have your choice of monthly payments, a contract, or just buying it outright for $576 on Sprint. Verizon only has payment plans, and the full price phone is a little more expensive.
Sprint is pushing customers to trade-in their old phones to pick up the G5, and is promising a minimum of $150 value on old phones. Of course, you'll probably want to wait until the G5 is actually out before you give Sprint your old phone. If you want to pre-order now, you can sign up for monthly payments of $24 for 24 months or $150 on-contract. It's actually $200 at the time of sale, but you get a $50 mail-in rebate.
Sprint's pricing for the G5 is looking quite competitive. AT&T is asking $100 more for its G5 variant ($688). As with other US carriers, you get a free spare battery and charging cradle too. Sprint offers silver, black, gold, and pink versions of the phone. If you prefer to take care of things face-to-face, pre-orders are available in-store tomorrow.
Meanwhile, Verizon is offering the G5 for pre-order today at $26 per month or $624 full price—Big Red doesn't do contracts anymore. This phone will ship on April 1st as well. Verizon offers a battery/charger with purchase, but also an LG 360 Cam. It only comes in silver or black, though.