I installed the latest hacked Google Maps (v3.4.0) on my HTC Magic tonight.
Recorded how it went here.
This version includes multi-touch support ported from the Nexus One OTA of a couple of days ago. I've tried it and it works very nicely.
It also (thanks to Brut.all) includes GPS Navigation support. This version is much better than previous versions. You still get "Unnamed Road" as the name of the street you are on, but the voice instructions are now much more frequent (about 80% or more tonight) and all of them were before the action needed to be taken.
Previous versions had seen the voice not happen about 70% of the time, and when it did, it was often at the very time you needed to be turning...or seconds after.
Maybe I was just lucky tonight, but the 30 minutes I was driving around using the GPS Nav on my phone was as close to the 'golden' experience we enjoyed for two weeks prior to December 7th when Google stopped fully-functioning GPS Nav to the rest of the world.