Apparating at Hogwarts?

[watsola79]

No: HPFGUIDX 88853

Forgive me if this subject has been covered already (I haven't seen 
any reference to it), but I was re-reading Chamber of Secrets 
yesterday, and I noticed at the end, after Harry set Dobby free from 
the Malfoys, that Dobby *vanished* with a crack like a whip.  Sorry I 
don't have my book with me, can't offer the exact quote.  

Now, apparating and disapparating have been described several times, 
always with the loud cracking noise....I think it's in the beginning 
of OOP when Harry hears the loud crack and thinks that it's exactly 
the sound of someone apparating or disapparating....also when Fred 
and George apparate in Ron & Harry's room at Grimmauld Place....I can 
think of several others....

Does this mean that Dobby disapparated from Hogwarts?  According to 
Hermione (Hogwarts, A History), and Umbridge, "You can't inside this 
school!"  Or is there canon that Dobby can appear/disappear through 
the use of other forms of magic?  If so, then maybe Hogwarts isn't as 
safe and/or protected as people like to think it is.

Food for thought,

--Lana Lovegood