Just in case anyone is interested, I'm working on a class (later a CMSms module) to do just this: Embed a Excel spreadsheet in an HTML page.
I find TinyMCE's table abilities difficult to work with. Besides that it doesn't quite work in Chrome, it's rather difficult to style unless you get into the HTML and CSS, which the average customer would rather not do. I do use it with success for a table on a page as part of the initial design, but can't begin to explain to the customer how to add their own tables and make them look good... Everyone knows Excel.
My class requires the user to save their Excel doc as an "XML Spreadsheet" (there is another XML option). This outputs XML data that has all the data, plus styling info into a file. You open the file into a variable, then input it into the class, plus optional arguments regarding which styling to take from the spreadsheet, then it outputs the appropriate stylesheet data, plus HTML table data. I plan on it understanding and translating attributes such as text formatting, justification, colors, borders, cell background, etc.
So far, I have it read the data and output a table with no formatting. However, it does understand horizontal and vertical cell merging and responds with the correct colspan and rowspan attributes. Not tested in Excel 2007 or OpenOffice yet.
The CMSms module would have a control panel which would allow the user to upload an Excel XML file, choose which formatting to take from the spreadsheet and it would provide the class name, so that the table can be further styled in CSS, along with the smarty tag needed to reference this document in their page/news article.
The idea came about during the re-design of my racing club's website. The points table is done in Excel. The site is currently managed with FrontPage, which being an MS app, it handles copying and pasting from Excel quite nicely. Example:
http://portlandkarting.com/gcsprint_results.htm . The redesign is using CMSms, and since this ability doesn't exist, we would have to save the spreadsheet as a web page and link to it, or utilize an IFRAME.
If anyone is interested in utilizing what I have, or further developing it, I would be happy to send what I currently have.