I had 2 aha-experiences in romania. First was a bill from hilton bucharest over 110 EURs for 1 week of highspeed wlan internet access.
Second, but much better aha-experience, was an offer from ZAPP, thats a local Wireless Access Provider in Romania, who offers a wireless interent device with usb connection for about 89 us$, this includes the chip and 23 hours of prepaid internet access. (a refill with additional 23 hrs is about 30 usd). It worked great in the city areas in romania; I tried it once using it on the countryside out of a moving train, but did not get a connection.
You can buy the zapp-device in all electronic stores and I also saw special zapp stores. Mobile communication is pretty popular in romania, there are a lot of cell phone stores.
What I liked very much about this solution is, that the connection speed was fast enough to use skype over it. So I solved 2 problems: mobile internet access and cheap phone calls.

p.s.: In Bucharest you can find cabs with the sign "internet cab", which are cabs with wireless lan. The technology behind it is a wireless lan router which is connected to a - zapp modem. :-))

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update 05.12.2007

My name is Dragos I live in Bucharest/Romania, I find the info from here useful so I contrib :)
GSM 800/1900 Mhz ; 3G 2100 Mhz
Cosmote: 0,80E/MB. www.cosmote.ro - only GPRS national
Orange: 0,90E/MB. www.orange.ro - GPRS/EDGE national, 3G > 100 cities, 3G+ > 5 cities (7,2mbps)
Vodafone: 1,00E/MB. www.vodafone.ro - GPRS national, 3G > 100 cities, 3G+ > 5 cities (7,2Mbps)

CDMA 450 Mhz
Zapp: 129USD+VAT for modem wireless + 70H +30H(after register)
reload card: http://www.zapp.ro/offer/data/zoe/zoecard/
CDMA max.150kbps national, EDGE max. 2,4Mbps > 100 cities

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update July 2009

Zapp was recently bought by Cosmote, which was missing a 3G license, although the Zapp service might still be there for a time. So you get to choose practically between Vodafone (3G), Orange(3G), Cosmote(2G), Zapp (CDMA2000 in 450MHz) and the new Digi.Mobil (3G).

Now regarding the Orange PrePay experience
So I just came back from Romania (home country ;-) ) and one of the nice deals that I found was from Orange - prepaid. Just buy the normal prepaid package from a shop - Orange PrePay was 4,- Euro with 4,- credit returned on it. Then don't forget to recharge - also at all shops - with the value that you'd like.

To cut to the Internet issue - you can activate the mobile Internet option with 2/4/6 Euro from your credit for 10/100/500 MB to be used in the next 30 days, then you pay 0.20/0.04/0.012 Euro/MB for what you do above that - so the same price as for the included traffic. I activated the 6 Euro one and was very happy, although you must be warned that the 3G coverage is not that wide as you'd like, but otherwise EDGE/GPRS still works ok outside of the big cities.

Then in Romania all the big fuss seems to be now about this mobile "options" that you can buy with credit from the prepaid cards. Some are good offers, some not so much, but the fact is that unless you get one, you'll run out of credit VERY FAST! For example at Orange, just like the Internet option, 5,- buys you 500 minutes+500 SMSs in the network and 50 minutes outside in any national fixed/mobile or EU fixed destination to be used in the next 30 days. Or if you don't care about the 500/500 in the network, you can get the 100 in any national fixed/mobile or EU fixed for the same 5,- Euro. There are soooo many options there, that you'd better just ask at the shops for what the offers at that time are - don't worry, most of the sellers speak English if not also Italian and Spanish.

All of the options are configurable from an operator menu, but reaching a real human to help was impossible and also very very expensive.