Valve has released the Team Fortress 2 SDK, which means we can expect a load of new content from the modding community.

Valve releases TF2 SDK to the public for modders, allowing changes ranging from tweaks to complete conversions. Modders can ...
Engadget

Valve hands the Team Fortress 2 source code to modders

Valve is handing Team Fortress 2 modders the keys to the kingdom, as long as they don't try to make any money from it. The company has added the client and server game code to the Source software ...
PCGamesN

Valve is making TF2 modding easier by waiving a $50K fee

The Team Fortress 2 modding scene is about to get a little easier, it seems, as Valve has apparently struck a deal with Microsoft to waive the $50,000 fee for the Havok physics engine for future mods ...
TechSpot

Valve releases full Team Fortress 2 SDK, modders gain control over the game's code

Why it matters: Team Fortress 2 launched 17 years ago but still receives significant updates, and its player base is as healthy as ever. The latest patch fully unlocks the game's SDK, releasing ...
Hosted on MSN

Pre-Fortress 2, a mod that bridges the gap between Team Fortress Classic and TF2, is coming to Steam with a whole lotta grenades

Team Fortress 2 modders love nothing more than imagining alternate histories for Valve's long-running multiplayer shooter, and this year has seen several of these nostalgia-tinged conversions migrate ...