Is Croatia using Euro now?

No, and it won't be for years.
The next new euro-currency country will be Latvia.

They don't have the Euro as official currency and they aren't part of the Schengen area yet.

Croatia has been a EU member for only two weeks. It's a long way in the process til €€.
Several EU countries have still their own currencies.

No, not yet, unfortunately - it would be much easier for us tourists if they used Euro.

I don't think Croatia is going to rush to join the Euro zone. It would probably force up prices, among other things.

Prices rising as a result of the euro is a bit of a myth - EU wide, they measured a 0.9% rise as a direct result of the first round of euro implementations. That's nothing compared to regular inflation. Remember, most early euro countries already actually used the euro as their currencies were fixed against each others for many years. Life got more expensive generally in many EU countries since the early 2000s and people like to blame it on the currency.
The change in the price of dining out has been much more dramatic in the Netherlands than in say Germany or France, so it's perhaps more to do with individual business owners trying their luck.

Hi!
Official currency in Croatia is Kuna (HRK) and exchange rate is (depending on the day and bank) 7,37 (seling) and 7,5 (buying) - approximate.
Restaurants etc. are allowed to accept EUR as a method of payment in case:
- there is no exchange office nearby (1 km radius I think)
- the exchange office / bank is closed (weekend, night etc.)

But, it is definetly advisable, if you are considering using EUR to pay for your dinner or so, to ask in advance if that is acceptable, and ask what is the exchange rate.

Have a good vacation!