Obviously, you know they have different meanings, because you are using different tenses in your own question. So I think your question is about style and convention rather than a discussion of each of the three tenses.
Yes, you will see all three used in software release announcements. A good copywriter or technical writer might prefer has been released or is released, because it implies a current event -- something people should make note of in the present moment. Software releases are often viewed as marketing events, and using present tense or present perfect tense makes something seem immediate and exciting.
Was released would be more suitable for press coverage, where the reporter/writer is covering facts ("an update was released today") and not necessarily trying to make the release sound exciting. Of course, many software publications are tied so tightly to the industry that they are really just a marketing arm for the software they're covering -- so you'll probably see present tenses more often than past.
Some publications and marketing departments will follow a style guide, in which case they probably have already defined what tense they prefer to use for announcements such as software releases. This would be the case at larger companies, obviously. At other companies, they might just copy and paste whatever tense was used in the previous announcement.