This is available in SSRS, where different document map keys map the output to different spreadsheet tabs when outputting to Excel. So if you create a document map with "Summary" and "Detail" separately the data is rendered on two worksheets.

We share the same problem and agree with the proposed solution.

I would very much appreciate the support of this as well. Our use would be similar to Wyatt's - Summary tab, 1-to-many Detail tabs. It would make sense to use the page break functionality and just create a separate worksheet tab for each new page.

I know that I can output reports to separate Excel tabs using a Report Book, but that's not a good solution when data dynamically determines how many tabs your report should output.  For example, I have an invoice report that outputs in the following group hierarchy.

[1] Invoice Summary (new tab)
[1 to Many] Facility/Department
    Summary (new tab)
    Detail (new tab)

Ideally, there would be a report property to export Excel in a mode similar to the Web output, where only explicit page breaks result in new tabs.  I cannot believe that isn't a more common request.  My clients constantly want summary data paired with detail data.  If they said data is in the same Excel tab, converting the detail data to a table, de-merges and re-sizes all the columns, which is a difficult to use, ugly mess.