Think I've heard of that App before, looks like it does support my camera so might be worth a try, but I'll have to get an adapter cable (£11.99 on amazon sure ebay'll have them cheaper)
Only problem is my phones got a fairly small screen which might be the same size as my cameras live view so no real improvement, might get myself a cheapo Android tablet one of these days though and if your doing startrails/long exposure stuff then your phones handy to play around on whilst you wait but with a tablet that's no issue.
Doesn't help Xentity too much though at the mo, the D70 doesn't support cable releases/live view so what we really need to do is pursuade him to buy a new camera, go on you know you want to