With the LEGO Group, they make it plain and simple for people wanting to use their registered trademarks (not a copyright or patent) - link already provided twice above. I really do not see what there's any issues about if people play fair
In the early days of LEGO bricks, before they started using ABS plastic, LEGO did patent a lot of their designs but so much has changed since then - for instance the standard 2 x 4 stud brick has, iirc, had at least eight different variations over the last 40 years. These days the LEGO inventory stands at something like 33,000 different designs of elements, hardly any of which are 'patented'. Most of the elements that are 10 years or older are publically available as basic 3D models via LDraw.org - even instruction leaflet/books are available for download via Peeron.com.
Anyhow, my point before was not about 'compatible with LEGO' items, copyrights or patents, but the phrasing of the Shapeways model titles as provided by the search link Youknowwho4eva posted that blatently use the LEGO trademark as the leading word. But, hey, if he don't care why should any of us.
The LEGO Group are approachable, they do communicate and help those who ask how their 'compatible with LEGO' items can be used - do the right thing by the LEGO Group, and they'll do the right thing by you.
Oh, just remembered, LEGO did have a Duplo play table that was a top and slot in legs on sale to the public, there are also many other LEGO designed play tables in educational/commercial environments that could be used as coffee tables. I would recommend careful research before releasing a modular table system based on anything like a LEGO product - easiest research in my books is just to email the people and ask, if they say 'yes', push for endorsement of the product, if they say 'no', you know where you stand and can move on.
Paul