最近做跨平台图形用户界面库选型，权衡很多因素后最终选择了Qt，其中一个重要因素就是Qt使用LGPL授权许可。由于本人对LGPL理解有限，始终对闭源商业软件如何发布Qt库存在疑问，其中最关心的是：发布的商业软件中是否可以包含（或附带）Qt的动态链接库（dll,so）。于是在网络上查找到如下相关资源：
官方的说法（查看原文“Qt: Making the right licensing decision”）：
LGPL
The LGPL is a license agreement written (and copyrighted) by the Free Software Foundation.
The LGPL is a “copyleft” open source software license but is less restrictive than the GNU GPL.
Facts:
The LGPL version 2.1 license was created by the Free Software Foundation and is copyrighted by them. This means that the terms cannot be changed or negotiated by us.
Users can develop proprietary applications that dynamically link to the Qt libraries without having to release their application source code.
All modifications that are considered “works based on the Library” must be licensed under the LGPL v. 2.1 and need to be shared with downstream recipients in source code format (i.e. contributed back). In the Qt context this means that modifications made to Qt itself must be licensed under the terms of the LGPL.
If you are shipping an executable, you must include any data and utility programs needed for reproducing the executable (i.e. must provide components needed to recompile with a new version of the library) unless such data and utility programs are normally distributed with the major components of the operating system on which the executable runs.
Copyrights and notices need to be maintained.
Because the LGPL is a complex legal document, we always suggest that you have your legal counsel review the license prior to beginning development work to ensure that the LGPL is appropriate for your development project. Please note that once you begin with the LGPL you cannot then convert to a commercial license due to a restriction in our commercial license agreement.
网友讨论：
“Qt之LGPL授权下的阴谋？” 来自 CSDN
“Freely distribute the Qt shared libraries (DLLs)?” 来自Qt官方论坛
我的结论：
闭源商业软件免费使用LGPL版的Qt必须满足如下条件：
1、不修改Qt源代码。
2、必须用动态链接的方式使用Qt库。
3、在软件版权声明中说明使用了LGPL版本的Qt、说明具体使用了那些Qt库，并确保软件使用者了解。
4、在发布的软件中包含Qt原有版权声明。
另：满足以上条件后发布的程序中可以附带Qt动态库（即打包在一个安装包中）。
参考：http://my.oschina.net/eechen/blog/66337