I'm just going to be blunt here. This is terrible. You have a solid background in a boring color, word art in multiple colors/fonts, and a logo that looks like you found it in microsoft word's clipart collection. It basically looks like something I would have made in second grade when screwing around in MS word.
Go look at professionally made posters to get some ideas. Stick with a single, readable font, and find a background that grabs attention without distracting from the information. And actually put some information there, not just a couple random slogans. You have to interest the reader enough to follow up on it. With what you have now, I have absolutely no idea what it's even f or, and it wouldn't interest me nearly enough to look it up.
Why do you need a poster anyway? It seems like such a strange thing to make if you're trying to attract software developers. Besides, my experience with programmers is generally that they care far more about the information than how it's conveyed. And they will want some real information. The best way would be to just concisely explain what you're trying to do and why they should want to be a part of it. Then fibd a more effective means to advertise it. The internet seems to be the most logical way, though I'm sure others could give more help with this part.