No PSN cards "at this time" for Europe and US [Update]
No news about North America, but Sony spoke to CVG and stated that no, in fact, they had no plans to bring the PSN cards to Europe at this time. In the future, perhaps? Maybe Sony Europe will take charge and set something up instead of leaving it to the main offices. CVG also points out that during the European launch of XBox Live, there was an issue of the same manner -- no plastic, no online gaming in Europe. Let's hope in the future, this is not a trend.
[Update: We contacted SCEA PR Manager Al de Leon about the availability of the Card in the US. "As far as the PLAYSTATION Card, we don't have any updates to the payment system to announce."]