historically, all new macs get the free update when they announce a shipping date (roughly) and price for the new version of os x. so if you bought a new mac today, you'll likely have to pay for mavericks. and as macdawg pointed above, you probably won't pay anything near $150. last year's upgrade was $20, and it was $30 the year before.
Snow Leopard was $30, Lion was $30 and Mountain Lion was $20, has there been a rumor that the price was going to substantially increase over the last release
Mac upgrades have been 20-30 bucks.... I hightly doubt it will be 150 they aren't microsoft. Apple screws you when you buy their hardware they basically give you their software to keep you.
After this announcement, you can go to http://www.apple.com/osx/uptodate/
where you can order your copy of OS X 10.9. This copy costs you nothing, if you have the proper hardware and/or purchase receipt.
Mac upgrades have been 20-30 bucks.... I hightly doubt it will be 150 they aren't microsoft. Apple screws you when you buy their hardware they basically give you their software to keep you.
Apple used to charge $150+ for OS upgrades too, you know... Plus Microsoft seems to be heading the way of cheaper software too, you were able to get Win8 for $40 for a decent period and the upgrade from 8 to 8.1 is supposed to be free. Of course Microsoft will keep their expensive PRO packages but I think their standard release is headed the way of Apple ($25 or less).