Is this expression correct "Don't worry about it; it is supposed be one of the features of this year's release"
Supposed to (pronounced /'spostə/) is a periphrastic modal idiom. I.e, it means much the same thing, in much the same contexts, as the modal auxiliary verb should.
Like should, it must be followed by an infinitive verb (that's what the to is for), and it indicates (like should) either a mild obligation of the subject to perform an active infinitive (the deontic modal sense), or a commonly-held belief in the likelihood of a stative infinitive being true (the epistemic sense).
- (You should/You're supposed to) lock the door behind you.
- This (should/is supposed to) be the last one we do.
Unlike should, however, supposed to is not a verb but a predicate adjective, and therefore has to be preceded by some form of be, which is tensed. Should, a defective modal auxiliary, doesn't allow any tense.
- You were supposed to lock the door.
- *You shoulded lock the door.
All modals have such periphrastic idioms, for the same reasons, often with idiomatic reduced pronunciations, e.g,
- ought to /'ɔɾə/ ~ should
- have to /'hæftə/ ~ must
- want to /'wanə/ ~ will
- (be) willing to ~ will
- (be) able to ~ can
- (be) allowed to ~ may
In the case mentioned, this is the epistemic sense, so it means
It is a commonly-held belief that this is likely to be one of the features of this year's release.
And that seems to be how it was intended and interpreted.
John Lawler's answer is fabulously detailed, but may be a little hard to follow.
In this sentence, "supposed to" has the meaning of "is expected to." It's similar to its meaning of obligation -- telling a child "You are supposed to eat your vegetables" could mean either/both of "you are obliged to eat your vegetables" and "you are expected to eat your vegetables."
As Mr. Lawler points out, "should" is often a good replacement. It has both the "obliged" and "expected" meanings.