I'm building a product which I hope to sell as Software as a Service. I've been working on designs of interfaces and have landed in something pretty similar to GMail interface. I think my app is looking as Gmail looks! Does anybody know if this can bring me legal issues for copyright or so?
If there is any issue at all, it will be in the realm of trade dress (trademark) rather than copyright. Please see "How Can I Protect the Look and Feel of My Website?".
No one can provide a solid answer here because trademark infringement analysis is fact-specific. If you want a definitive analysis, you will need to retain a lawyer to analyze and compare your site and Google's.
Disclaimer: This post does not constitute legal advice and does not establish an attorney-client relationship.
As long as its not a Gmail clone or you are not stealing any code you should be ok. The thing i wonder is why you would like it to look like Gmail?
Gmail has a horrible ui, as do many google products. If you are looking for inspiration, maybe you should fashion it in the essence of mobile me, or even better gmx.com
last, if your SAAS is web based email you should really study the market. Web based email is not profitable unless if you have a very specific niche.