It appears Adobe accidentally leaked Lightroom for iPad before the official announcement. It looks like the app will be a cloud subscription of $99 on an annual basis.
There may be other purchase options when it officially launches.
Adobe's marketing for Lightroom for mobile is “Take Lightroom anywhere.” According to an Adobe employee, the software will have a lot of the same features currently in Lightroom for desktop.
Source: [9to5] via [MR]