According to nu.nl Vodafone has reduced their prices for UMTS today. Traffic will cost 0.50 euro/MB (I assume that their usage of Mb is ignorance). Compared to ‘normal’ traffic, this is obviously quite expensive, but this is obviously not a fair comparison. When you compare it to other types of mobile costs it is quit affordable (for example one SMS message of 160 bytes: about 23 9 8 cents).
Let’s assume you’re streaming a 64 kb/s video. For one minute, this will cost you about 0.25 euro (cheaper than calling for one minute with a pre-paid card). What about VOIP-over-UMTS, way cheaper than calling :) (but, seriously: this wouldn’t work, the delays for UMTS data are probably too high for that).