BOINC FAQ: BOINC and Open Source
From Unofficial BOINC Wiki
[edit] Is the source code available?
Yes the source code is available, at least for some of the software. See: Source Code Availability for more details.
[edit] I tried to compile the project and failed. Is there any help out there?
Yes, there are mailing lists, web sites, and more information in the Wiki. Look at these:

