What's not in this update? The new game mode that Valve had previously promised.
While Valve stands to profit from selling in-game items, so does the community. The in-game store FAQ notes "community contributors will receive a percentage of sales on items they've created."
The Mann Co. Store may be goods news for the lazy, but the miserly needn't be overly concerned about the change. Valve notes in its new Mann Co. Store FAQ that the Polycount Pack items are unlockable and craftable through normal means, just like other items.
Read more about the new "Mann-conomy" in the service's newly released FAQ and peruse the new item sets at the Team Fortress 2 official site to see if that five dollar Spy knife is something you'd like to buy.