There is a lot of innovation going on in the Office 2.0 department these days. Some great use cases are coming out of it. I've sat across the table from a fellow copywriter - spitballing headline ideas and writing them into the same Google Document at the same time.
But fundamentally, people still use Google Docs or Buzzword (and Buzzword is very cool!) to write stuff - just like they use MS Word.
Excel is a different story. Nearly everyone uses Excel to do things that it wasn't conceived for.
Most people use spreadsheet programs to organize things - but spreadsheets were conceived and designed as an accounting tool. Accounting and organizing are definitely related, but they are definitely not the same thing, either. There is some real innovation to be had around organizing information - phone lists, sales leads, sports schedules, etc.
Other organizers exist, but none have really solved the problem - because none are as flexible, or powerful as a spreadsheet - so that's what most people continue to use.