Budgeting and Planning is a highly iterative Human and Document centric process where the ability to change the business logic and rules is crucial to keeping the application relevant to business needs. With SharePoint 2010 you are able to put together a Composite solution to take care of rolling up and down plan and budget from the CFO to the lines of services. You are also able to provide Business Process Awareness using a Visio Services web part to allow visibility into the process and escalate when needed. With SharePoint 2007 you are able to take a different approach where each line of service hold their own planning/Budgeting spreadsheet and the information is rolled up/down using SQL Server Integration Services ETL process and then viewed using SQL Server Reporting Services.
 
Please see here a short video demonstration of the two approaches

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