Malloc will in some cases return null when the allocation is too large. This might happen long before system is out of memory and it is very much indeed preferred and practical to abort allocations in those cases.
Those are rather specific cases, though, aren't they? I'd imagine malloc only returns NULL when virtual address space is exhausted, not physical memory. So if you make an exceedingly large allocation for a very specific, massive thing, then yes, you might want to handle that. But if your allocation was rather small, then you are back to what your parent commentator said and are probably better off aborting.
The only time you should avoid checking malloc() return values are for special mallocs that really cannot return NULL. One example is FreeBSD's kernel malloc() when called with the M_WAITOK flag.
On a 32bit process that is easily achieved and also if the virtual memory has been fragmented.
I've encountered many situations where malloc will return null in real world applications. Some of which we really wanted to handle that scenario and fail gracefully or continue with less memory usage (and thus less performance).
