A very nice article about consideration of developing software product, here is a quote:

Most projects carried out by internal IT organizations suffer from budget overruns that occur for two reasons: excessive customization and changing requirements. In an effort to keep external customers—especially big, powerful ones—happy, many IT groups end up overcustomizing solutions and adding needless costs and complexity. One large consumer credit company almost doubled the time and money originally allocated to a new platform for institutional customers by trying to satisfy all of their operational and technology needs.

http://www.mckinseyquarterly.com/article_print.aspx?L2=13&L3=13&ar=1697

The other recommendation of developing good product for mobile device - http://www.allaboutsymbian.com/features/item/A_Developers_Guide_To_Marketing_Software.php