You can now explore the Island's towns (e.g. Castletown, Douglas or Ramsey), glens (e.g. Silverdale Glen, Glen Helen and Glen Maye), historic monuments (e.g. Lady Isabella or the Laxey Wheel, Corrin's Tower on Peel Head, Peel Castle, Castle Rushen in Castletown and Derby Fort on Fort Island, Langness) and the only mountain (Snaefell) or anything else that can be seen from above.
Unfortunately there still isn't any name data, so it's much easier if you know what you're looking for when exploring.
Update: I see from the Isle of Man Newspapers website - Improved Isle of Man images on Google Earth - that the imagery being included in Google's database is dated 2006 and is the result of "months of negotiations involving the Department of Local Government and the Space Commerce Division of the Treasury."