iPad 2 Sold Out - Out Of Stock

Weekend sales of Apple's iPad 2 were stellar with as many as 500,000 tablets sold to mostly new tablet owners, according to Piper Jaffray, an independent market research firm. Sales of the iPad 2 were up 67 percent compared to the launch of to original iPad when Apple sold 300,000 tablets.

The figures reinforce Apple dominance in tablet sales as first-time tablet owners flock to the iPad 2 and not tablets such as Motorola's Xoom tablet based on the Android mobile operating system.

(See Related Video: Unboxing the iPad 2 and Smart Cover)

Piper Jaffray says it spent the weekend calling Best Buy, Target and Apple Store locations to get a handle on availability for the iPad 2. It discovered most stores were sold out. "We were unable to find any availability," wrote Gene Munster, Piper Jaffray analyst, in a research note Sunday.

It's unclear how many stores Piper Jaffray called to determine iPad 2 availability. Apple's online store currently indicates new iPad 2 orders will take three to four weeks to ship. On Friday, the iPad 2's shipping window was one week.

iPad 2 Customers Mostly New to Tablets

Piper Jaffray says it surveyed 236 prospective iPad 2 buyers in line at Apple Stores in New York and Minneapolis. Piper Jaffray determined that about 70 percent of iPad 2 buyers didn't own the original iPad, suggesting the iPad's user base is growing.

Read More: PCW