I haven't seen any rumors about any new iPhone any time soon. I would repair.

Probably the main reason is that these devices are still so new and seem to attract so much attention that you wouldn't want people looking at your crack (no pun intended). Just like you wouldn't wear an attention getting watch that had a cracked face...

Edited: What I had heard is the next version of the iPhone will be a 3G model. Jobs had said late 2008 (but that was about 3 months ago).

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2008 X5 4.8i | Wheels: Summer> style 336 20" RFT; Winter> style 214 Ferric Grey 20" RFT | Aero kit | ESS E-Flash tune | V1 | LCI Rear Tail Lights | Coding completed | Engine replaced at 90K