I'm working with LR 3.4 on a Mac with the latest camera raw and any current updates as required I've encountered the following problem.
When I export a print collection it reverts to a standard collection with no layout information when imported back into a different catalogue. The physical files are retained but the print layout is lost and the interface icon for a print collection changes to show that it is no longer a print (layout) collection.
Part of my workflow entails prepping my best (IMO) images for my portfolio gallery. The way I do this is to gather the images into a collection set, then create individual print collections with, say two or three images to a page, with borders etc. I then print to file as hires JPEGs, because we can't export from the print module, import into Photoshop to add a watermark via an action (I know this can be done in LR but I want only one watermark per image set not one per image) ready to upload to an online gallery. I prefer to use individual catalogues for each client or shoot and archive when completed. So my method is to export my best 'picks' to a new temporary catalogue from the working catalogue, and then import the temporary catalogue contents back into a specific gallery catalogue. This way I have my best work in one place and can maintain and vary the portfolio gallery as I choose.
No matter which route I've tried so far, I've only managed to export/retain the collection contents and not the print layout itself.