Everyone knows that the iPad 2 is going to be giant. Immense, even, depending on your definition of the word. & now an analyst’s estimated that Apple will sell 600,000 of the devices this weekend, once the number of first-generation iPads that sold in its first 24 hours of availability.

Analyst Bran Marshall of Gleacher & Co. isn’t alone in that belief. Bloomberg’ Adam Satariano, who interviewed a few specialists, said today that he’s  “one of several who expect the iPad 2 to outpace its predecessor. Apple sold 300,000 of that version in 24 hours.”

Meanwhile, Forrester” which predicted earlier this month that the iPad 2 will claim a U.S. tablet market share of 80 percent in 2011 ” reasserted its confidence yesterday, indicating that Amazon represents the only feasible competitor.