I think Pakistan has the most devastating bowling attack especially in SA conditions. Waqar, Wasim, Shoaib, Razzaq(Azhar Mehmood), Shoaib Malik(Saqlain Mushtaq) is a potent attack which can threaten any of the current lineups.
Australia has the next best lineup with McGrath, Gillespie, Warne, Bichel and Lee in the front line and a host of useful bits and pieces players who can turn their arm over.
SA should be a good attack in their conditons with Pollock, Ntini, Telemachus, Kallis, Boje, Klusener, Hayward, Ngam....
The next best attack could be NZ with Bond, Cairns, Styris, Vettori, Harris and co.
England comes next with Gough, Caddick, Tudor, Flintoff, Cork and Giles.
The West Indians and Indians can be bunched together with Dillon, Collins, Cuffy, Nagamootoo... for the Windies and Khan, Nehra, Agarkar, Kumble, Harb... for the Indians.
SL has Murali and Vaas and some others like Fernando and Perera.
The other teams including Zimbabwe don't really have a bowling attack to speak of.