They're just taking a leaf out of Apple's book - gift certificates are very popular on the iTunes Music Store.

This continues the meme of Skype credits as currency.

I hope these will be available in shops or somewhere in major cities to buy over the counter.

So many people are having difficulty getting credit because valid credit cards are rejected or Moneybookers does not work that an alternative is required.

Or maybe some kind person could buy them and sell them privately - transferring them after receiving a cheque.

And you get 3% credited to your Skype account when you buy (it actually worked when I bought the certificates).
Their other announcement about Skype Credit was a bit of a letdown. I thought I was able to use my SkypeOut balance to buy ringtones etc already!
Not that I would ever buy a ringtone for Skype, on a mobile there is significant difficulty in installing the tone yourself, but on a PC...
Actually it would be interesting to see how the market for ringtones is doing on mobiles, as the sophistication of the platform (handset) increases.