It's the solid fat crystals you need to stabilise the pastry structure, they're also important in bread and cake manufacture too.
As Arch states, you can of course use naturally hard oils such as coconut or Palm, but they are expensive.
(The sensible thing to do would be to take cheap and plentiful oils and fully hydrogenate them (no trans fats) to get hard fats and then blend them with softer oils, but since the media mis-informed the population that won't happen).
The other way that I am aware of is a process called 'Interesterification:
Fats/oils consist of a molecule of Glycerol to which 3 fatty acids can be attached by a reaction called esterification. Fatty acids come in different lengths from 4 Carbon atoms long (giving butter it's distinctive whiff) to 22 carbon atoms long and may be either saturated (giving hardness) or unsaturated (giving fluidity). During interesterification, you 'simply swap the fatty acid chains around to create distinct species where for example each Glycerol molecule has 3 saturated long chain fatty acids attached rendering them harder and others have shorter chain or unsaturated fatty acids rendering them fluid at room temp. Seperation of the 2 fractions is a case of cooling them to a certain temp and spinning-off the hard crystaline molecules.
Or something like that!
,Here:
http://en.wikipedia.org/wiki/Interesterified_fat