I wrote an article for DevX.com that has just published. Feel free to read it at the following location: http://www.devx.com/dotnet/Article/35324
I wrote this article as a starting point to better understand how to get Excel data into SharePoint, as a client of mine had some seemingly simple business requirements (get a ton of data out of a ton of Excel 2003 spreadsheets, and into SharePoint 2007) which ended up being quite complex to fulfill.
I hope you enjoy the article.