We’ve been bringing you reports for awhile now that Apple was preparing to launch a major update to their MacBook Pro line of computers. Rumored features include a retina display, USB 3.0, and a thinner (though not MacBook Air-like) form factor, which will involve ditching the computer’s optical drive (because who uses CD-ROMs anymore, honestly?).

While nothing has been confirmed yet, regarding either the features or even the fact that a new line is coming, there has been some strong evidence. First, supplies of the MacBook Pro started to run low. That’s always a good sign that something new is coming. Another strong indicator is when retailers start lowering the price of their existing inventory. That, it seems, is what’s happening now at Best Buy. They’ve reduced the price of all models of MacBook Pro (13-inch, 15-inch, and 17-inch) by $100:

The fact that Best Buy is starting to reduce the price of their inventory – even by $100 which, let’s face it, isn’t a lot in this context – is perhaps the best evidence yet that the line will be getting a refresh. Current speculation puts the new MacBook Pro line (along with updates to the iMac and MacBook Air, possibly) coming sometime over the summer, possibly as early as June. There’s a decent chance that they’ll release alongside OS X 10.8 Mountain Lion. The release date for Mountain Lion is expected to be one of the big pieces of news to come out of this year’s Worldwide Developers Conference, which is scheduled for June 11-15 in San Francisco.