(LPVOID) NULL: unnecessary cast?

[Francois Gouget]

I have noticed a lot of constructs of the form:

HRESULT WINAPI DMUSIC_CreateDirectMusicScriptImpl (LPCGUID lpcGUID, LPVOID* ppobj, LPUNKNOWN pUnkOuter) {
   IDirectMusicScriptImpl* obj;

obj = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(IDirectMusicScriptImpl));
   if (NULL == obj) {
     *ppobj = (LPVOID) NULL;
     return E_OUTOFMEMORY;
   }

What's the point of casting NULL to (LPVOID)? Isn't it already a void* 
anyway? Is it to fix a warning issued by ultra-recent gcc versions? (gcc 
3.4.2 does not complain here)

Similarly there are a lot of casts like this:

*ppobj = (LPVOID)&This->UnknownVtbl;

Again I thought any kind of pointer could be assigned to a void* 
pointer so is this cast really necessary?