If you look at the wiki page for LGPL, and the terms themselves, it clearly states that there are several instances where LGPL code can be bundled into and with commercial products, and the resultant code does NOT need to be made public. It also states one can put copyright and other such restrictions on the resultant work, so long as it includes the proper text showing it contains LGPL libraries. See section 5 & 6 in particular for exact terms.