It's to early to answer this question since the new OS X Leopard (10.5) is not out yet.

The obvious question here is, whether Skim annotation will be compatible with and convertible into the new Preview annotation. Will the the valuable and time-consuming annotations made in Skim be lost one day? Apple's new version of OS X, nicknamed Leopard, is rumoured to have extensive new annotation features build into Preview (Note: Apple took care to suppress information on the new Preview features a page that had detailed information has since been mostly deleted ). While you may loose your 50 kilos of scribbled on print outs when you move to your next job, the digital equivalent of this may happen when you upgrade to the next operating system or change computer. You can, however, engrave the annotations in the PDF, at which point they can no longer be separated via the Skim export.

Currently, if you open a Skim-annotated PDF with a different PDF viewer like Preview, you will see the bare PDF. It is also superior to a two file system of a PDF paired to a comment file. This is welcome since it allows you to remove your annotation before printing or passing on the PDF to a colleague. Instead, it attaches annotation info to the file. Skim doesn't change the original PDF like you can with Acrobat.

dedicated pane listing your notes searchable and hot-linked.

paper-like annotation including colour-highlighting, underlining, circles, boxes, full sticky notes, and anchored sticky notes that expand when clicked.easy searching using a pane on the left list all hits with page number and marks them clearly in the text after selection.facilitates reading PDFs with full screen mode, many zoom shortcuts, reading bar.

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