The question of whether in-app transactions are included in Apple's Top Grossing chart is one developers have been pondering ever since the new chart was created - in the iTunes 9 release in September.

US publisher Freeverse - perhaps the only company to have made a success of in-app transactions prior to the release of Tap Tap Revenge 3 and Rock Band - has done some number crunching and reckons it does.

It's compared the metrics for some of its current games in the US Top 100.

In terms of the plain US Top 100 Paid chart, Top Gun ($1.99) is #60 while Flick Fishing ($1.99) is #72.

However, when it looked at the Top Grossing charts, the positions are reversed - Flick Fishing is #97, while Top Gun is #100.

Obviously the only way this could have happened is if Apple is taking into account sales revenue generated by the 99c Private Beach expansion pack available within Flick Fishing.

Even more significant is the impact this could have in terms of Apple's new free-plus-paid option for developers and publishers.

This allows games to released into the Free chart, which include in-app transactions for more content. The first game to do so is ngmoco's Rolando 2, in which you have to pay 99c/59p to unlock additional chapters.

It's currently racing up the Free charts, but doesn't yet appear in the Top Grossing charts.

However, if developers start to see such free titles appearing in the Top Grossing chart, expect a shift from paid to free apps.

You can read Freeverse's full blog post here.