This is an example of what is possible when web services is baked into the platform. Excel Services in MOSS 2007 supports the creation of User-Defined Functions (UDFs) in .NET. The .NET methods show us as @ functions within the Excel spreadsheet, pretty nifty. Inside the UDF function, which is just a normal vanilla .NET method, you can do ... anything.
Like... for example... call a web service. And that web service could be running under WebSphere, or WebLogic, or .. anything.
What this means is you can very easily create UDFs for Excel Services, then have server-hosted spreadsheets in MOSS 2007 use those UDFs in cell formulas. The UDFs can call out to essentially, any remote resource in your distributed network - retrieve a result from a WebSphere analysis application, or an Oracle table, or a WebLogic process flow, etc.
Go forth and interop!