This is similar to the "alot" vs "a lot" argument. Technically, alright is not a word. It is a lazy way of writing "all right" to the point that it has actually become accepted. Go ahead, open up Microsoft Word and type it in. See, no red squiggly line under it (Now do it with alot just to test your sanity). It has even been accepted into the dictionary.
To be on the safe side, always write it out as two words. While it may be acceptable, it is still not taken seriously by the intellectual elite. But then again, who cares about them, go ahead and use either form without abandon!
Seriously, it really is two words.