Google Maps has added public transport info in several capital cities, but Melbourne, Sydney and Brisbane are still out in the cold
UPDATE: We've just
heard from Google that only Perth and Adelaide have access to Google
Transit. According to Google Australia spokesperson Rob Shilkin 'Overnight, some
grey lines between publicly known Melbourne tram stops were
inadvertently superimposed on Google Maps on the "Transit" layer.
They're being removed as they don't represent actual tram routes.
However, our users tell us that they're keen to see Melbourne public
transport information on Google Maps, so we'd love to incorporate it as
soon as possible and are working towards this!'
For once, Melbourne gets something before Sydney!
That's right, Melbourne is among 50 cities worldwide to receive the Google Transit treatment.
Fire up Google Maps today, navigate to Melbourne, and you'll notice a new checkbox in the 'More' dropdown. Tick 'Transit' and you'll be greeted with the new layer that shows you the main public transport routes in the city.
According to Google LatLong blog, the 'Transit Layer is a part of Google Transit. Whereas the main Google Transit product has the goal to provide full schedule information and routing, the objective of the Transit Layer is to overlay lines visually on Google Maps.'
So the Transit layer isn't quite as useful as it sounds. In Melbourne you'll find plenty of detail about tram routes (with links to timetable information from the relevant authority), some information about train stations (where they are) but absolutely no information about bus routes.
There's plenty of extra detail in other cities - in particular San Francisco, Paris and London, so perhaps the extra detail is coming soon.

Above: Melbourne, with the Transit layer turned on
Interestingly, if you visit the Google Transit you'll see two other Australian cities listed (but alas, no Sydney or Brisbane). You can access full timetable information for Perth and Adelaide, but the Transit layer is available only for Perth.
Another point, as noted by Jason Kincaid at TechCrunch is that even though Transit information is available it's laid out against the geographical map rather than a concise 'stylised' map - something that can make working out how to change lines more difficult.

Above: London, with the Transit layer turned on
Still, like other Google products the price is right -- it's free -- and the level of detail, information and usefulness is bound to improve over time. In fact, I fully expect that the next version of Google Maps for mobile to include transit and timetable information where possible.