This salvation, which was first announced by the Lord, was confirmed to us by those who heard him. God also testified to it by signs, wonders and various miracles, and gifts of the Holy Spirit distributed according to his will. (2:3-4)

How did the recipients of this message know the good news of God was true. The writer gives 4 ways:

It was authoritatively announced by Jesus Christ
It was confirmed to them by sure testimony from eyewitnesses (and earwitnesses)
God testified to it by signs, wonders and various miracles
God testified to it by distributing various spiritual gifts according to his will

An authoritative message, credible and sure testimony from witnesses, unmistakeable miraculous attestation by God and personal experience of spiritual gifts from God. Four different categories of attestation.

There is some debate about whether God continues to testify to it today by signs, wonders and various miracles, or whether these were authenticating the apostles as the message bearers. While I don't doubt that the signs authenticated the apostles message (and think the debate needs to be handled very sensitively in the UK at least), I tend from scripture to the view that God still uses signs, wonder and miracles for three reasons (none of which are that I have a great deal of personal experience):

It doesn't say that the signs testified to the apostles, but to the message. That is, they are not signs of the authority of the messengers, but of the gospel
It seems to belong syntactically with the next clause "and gifts of the Holy Spirit distributed according to his will." He was clearly distributing supernatural gifts more widely than the apostles to testify to the message, why then not sings, wonders and miracles?
God gave them to testify to the gospel. The need for God to supernaturally testify to the gospel still exists. I am uncomfortable with the idea that now there are preachers and a completed canon of scripture (which I wholly affirm), that this somehow means God's supernatural testimony is somehow redundant (of course you could maintain that it is entirely subsumed within the supernatural act of Spirit-inspired preaching, but I think the case is weak. Interestingly one of the main cases that gets made for the cessation of prophecy is Hebrews 1:1 - God used to speak through prophets, now he has spoken finally through his Son who is greater than the prophets. Ipso facto, no more prophecy. I think 2:4 shows that argument doesn't work as God is giving testifying spiritual gifts after the Son has delivered his authoritative word, as testimony to it)

Two reflections:

1. Wherever you come down on the question of signs and wonders, the writer to the Hebrews is clear what they were (and are?) for - testimony to the great salvation found in Jesus Christ. I was recently asked "if Acts type miracles don't cease with the closure of the canon, why don't we see them much today?" I rather suspect that the answer is because we don't want to put ourselves in Acts type situations today. If our lives were threatened daily, if there was a lack of Bibles among people crying out for the word of the Lord, if we were being dragged off to prison, I think we would. And in places where that is happening to Christians, I think they do. If you want Acts miracles, live in Acts situations. Don't think that we can live cushioned with comfort and be likely to get miraculous gospel signs as additional perks

2. The reason for God giving spiritual gifts, according to the writer, is testimony to this great salvation. Gordon Fee helpfully says the writer "would not have appealed to the evidence of these miraculous manifestations if there was any possibility that [his] readers would reply that they had never seen or heard of such things. They were matters of common knowledge and wide-spread Christian experience, and the reference to them here is calculated to restore the readers' faith in the gospel as God's authoritative message."

I infer that when spiritual gifts are denied in a church, it diminishes God's testimony to the salvation of Jesus. And, by the same token, when spiritual gifts are strongly affirmed in a church but not for that purpose, it similarly diminishes the testimony of God. They are given as supporting evidence to the authoritative word of salvation announced by the Lord. We need to watch the order that the writer gives and not give more prominence to spiritual gifts than to the message they are meant to testify to.

Application? I want to use my spiritual gifts to testify to the great salvation in Jesus today.