kas1e,

TinyGL now supports GLSL 1.20, which is what is mandated by OpenGL 2.1, which is the newest version of OpenGL that R300, R400 and R500 can support. GLSL 1.30, which is what is mandated by OpenGL 3.0, introduces for example integer variables in shaders, which the R300/R400/R500 does not and cannot support. So until the R600 driver is done, no newer version of GLSL can be supported.

beworld has been super helpful and tested a lot of things with shaders already, which has lead to a bunch of bugs being found, which will be fixed in an upcoming TinyGL update, which again will almost certainly be ready this week. What this means is that unless you want to be on the bleeding edge of testing, you can easily wait a little bit and let others test and get bugs ironed out before trying it yourself.