Lifehacker just reported a Mapplets feature on Google Maps, which is only available if you go to the Google Maps Preview site (which once you start using, is available to you on the normal maps address). It all looks pretty cool, being able to put layers of information on Google Maps itself, rather than having to go to the individual mash-up sites.
There will still be a place for mash-ups, since you can’t customise the UI too much, but as the map equivalent to iGoogle gadgets this looks great!
One of the more fascinating mapplets I’ve found so far is ‘Zürich Travel Time Visualization’. It shows how long it should take to get to parts of Zürich using a colour overlay.
The Lifehacker post also had a YouTube clip attached to it, so I’ll attach it here too for completeness :o)