Also maybe it flopped because Google built it themselves from scratch, its a departure from their other products which are usually acquisitions or based on an existing codebase.
Picasa was great before Google bought it. Talk is built around libjingle, Google Earth is rebranded acquisition, Chrome is built around webkit, Android is built on Linux, Google Docs is a rebranded acquisition, etc.
On the contrary; Gmail's probably Google's most successful non-search product, and they built it all themselves.
And obviously, their core businesses (search and advertising) were all developed by Google.