Since interest seems to be increasing, here is a comprehensive list of all Adds and Changes to Excel Object Model since 2003:
http://msdn.microsoft.com/en-us/library/bb149069.aspx

As a side note, if you are going to use 2007 methods/properties in a mixed shop it might be beneficial to call them in a wrapper. In this way you will work as expected in either version. Here is a simple example of how to do this:

[vba]Sub Test()
ColorRange Selection, Excel.Application.version, 6
End Sub
Sub ColorRange(rng As Excel.Range, version As Double, ParamArray args() As Variant)
With rng.Interior
.colorIndex = 6
.Pattern = xlSolid
If version >= 12# Then
'Because the property name is stored in a string this will still compile.
'And it will only get called if the correct version is in use.
CallByName rng.Interior, "TintAndShade", VbLet, 0
End If
End With
End Sub
[/vba]

Edit:
Just occured to me you could put version inside the wrapper instead of passing it as a parameter. (I know... duh)