the htc maps with the preloaded cached maps is on the thunderbolt but I am not sure about HTC's navigation client. google navigation is thee and that rocks.
the HTC nav is better, it has better voice guidance and it integrates with your phone so you can use navigation and when you get a call, it doesn't take you away from your navigation screen and stuff... I hope they didn't remove it
Google Navigation might be nice but Locations (Navigation client) has the ability to search POI's and also store addresses, download new maps and voices.
Google Nav sounds far too robotic.... (yeah i know "DROIIIIID") but still, its one of the reasons i still use my Garmin over the Google Nav