This is kind of like saying you won't invest in Facebook or Google or Apple until their price stabilizes. Either it's worth it to you or it's not. Stability is overrated in a world where pricing updates can be automated. If you're concerned about exchange rate risk, what you do is keep your funds in a more stable asset (like USD) but ready to be converted. Put a small amount of USD in an exchange and you'll be able to buy when you want to without this exchange rate risk.
At least facebook and google and apple have liquidity. All bitcoin has in that regard is a bot on mtgox that makes large fake bids and then moves them 50 cents cheaper if the market actually reaches that price.
