Webkit tries to scale content to fit to the width of a page. If there are very wide elements, the scaling makes the page unreadable. There should be a min horizontal scale factor to prevent this. Repro case: http://snowplow.org/martin/printtest.html Firefox does not scale the content to fit, and thus simply clips the long line in the test above. This bus was reported to Chrome (crbug.com/49698), but also occurs in Safari.
I cannot reproduce this with Safari 5.0.5 on Mac OS X 10.6.7. What version of Safari and on what platform are you seeing this with? We do have a minimum scale factor, which is set to 2x.
I tried on Windows 7 with Safari 5.0.5 (7533.21.1). Printing to Adobe Acrobat produces the attached PDF. It looks like an effective scale factor of about 16x is applied.
Created attachment 91023 [details] test output
Thanks! I don't have Windows handy, may I ask for one more thing? Could you try this with a nightly build from <http://nightly.webkit.org/>? It doesn't replace your installed Safari, and doesn't affect it in any way at all - and I have a suspicion that this may have been fixed already.
Created attachment 91029 [details] Output with nightly (r84630) There's a marginal improvement with the nightly build, but not much. Maybe 16x->8x