Digital Smoke is supporting iPad with Universal Applications of its Solitaire City games

With iPad's launch a couple of weeks away, developers are scratching their heads about what business model to follow.

One that seems to be picking up momentum is to release what's called a Universal Application that supports both iPad and iPhone and iPod touch in one download.

The advantage is you don't have to deal with multiple versions of your games on the App Store, and it also means that if someone buys the iPad version, they can also install the game to their iPhone (and vice versa).

The disadvantage is that you can't charge more for the iPad version of your game, and that the size of the download is increased.

Developer Digital Smoke - which has just announced its Solitaire City games are coming to iPad - gets around the first of these issues as it has three versions of its game already available, which will all support iPad.

There's a Lite version, plus a 99c Classic and a $5.99 Deluxe version.

Presumably it will be hoping that new iPad owners will be more happy to buy the Deluxe version, compared to Classic version likely favoured by iPhone and iPod touch owners.

And, of course, if you already have one of these games for your iPhone and you're planning to buy an iPad, you'll be able to get the iPad version for free too.

You can see the full list of announced iPad games on the Pocket Gamer big list of iPad games.