The big enhancement for version 2.0 is the ability to create and edit Microsoft Excel spreadsheets. Documents To Go version 2.0 supports the creation and editing of Excel 2007/2008 spreadsheets and can read files going all the way back to Excel 97. (Yes, Excel 97, as in released in 1997!) Version 2.0 also includes typing speed improvements over the previous editions.
Documents To Go (with and without Microsoft Exchange attachment support) is a free upgrade for existing Documents To Go customers. Don't already have Documents To Go? You can purchase Documents To Go (iTunes link) for $9.99 or Documents To Go with Exchange Attachments (iTunes link) for $14.99. Documents To Go v2.0 requires that you have iPhone OS 3.0 or iPhone OS for iPod touch installed on your device.
For more information about Documents To Go for iPhone OS, visit the DataViz website.