How can I be sure the version of New Vegas I'm currently playing is the latest one? I just received my copy and it seems Steam downloaded and installed the two patches. Is Steam reliable in terms of always keeping your game up to date?
What is the latest version now? When I check the main .exe it says it's 1.1.1.271 ...

Im not sure, there seems to be a new patch every day.

1.1.1.271 is what I currently have as well.

Steam will always keep the game up to date.

Not always . Looks like the Eastern European version designated "fallout new vegas enplczru" has not been updated yet, even when playing the game in English. It's still 1.0.0.240 for me.

It means basically one thing if there is no patch applied with Steam. There is no patch for that game version yet. It COULD mean Steam doesn't have the patch yet, but I doubt it.

All patches go through Steam, I don't think there are even manual patches available? Steam should always be the first to have one.