you can use any set of earphones with that adapter, but you won't have the mic/clicker that's on the Apple headphones. I believe Belkin is making an adapter that has the mic/clicker built-in, but it seems to me like it would put the mic pretty far from you mouth.
I ordered a Rivet earphone set that includes the mic/clicker yesterday, since my clicker died om my Apple headset. I also picked up a free replacement from the Apple store this afternoon.
We should have a few more choices for you in the near future. We are trying to expand our line and offer a few choices at various price points and also at least one other high end option in addition to the Apple/Etymotic hybrid. I think we'll have 8-9 prototypes in next week . We've had tons of feedback from everythingiPhone.com users, and we value your input and suggestions, so keep them coming!