It appears that the SourceMod engine split happened in the 1.5 branch a few days ago, starting with hg3865. I'm not sure what this means for the SourceMod 1.5 release, though. These games will still load extensions ending in .ext.2.ep2v.dll and .ext.2.ep2v.so for the near future, but these extension should be switched to .ext.2.tf2.dll and the like instead (hl2dm, dods, css, and tf2 are the ones that replace ep2v). Each game has its corresponding hl2sdk as well.
Nuclear Dawn has also split from L4D2 and has its own extensions ending in .ext.2.nd.dll/.so. It also has its own hl2sdk.
A few other fixes have been added in the past few days, including:
- SourceMod is now being built against MM:S 1.10 instead of 1.9.
- SourceMod is (finally) looking for mapcycle.txt in cfg/ as well as the game's base directory (for all games or just for HL2: DM, DoD:S, CS:S, and TF2 I'm not sure)
- Fixes in the cstrike module for getting prices.
- cstrike now has a CS_IsValidWeaponID function.
- Fixes for an SDKHooks crash.
- SteamAuthstringValidation is now disabled by default... apparently it wasn't always working. This feature is now considered experimental.
Keep in mind that it will still be enabled if you installed SourceMod before this and haven't edited addons/sourcemod/configs/core.cfg