Your are right that the Android mobile OpenCL system is fragmented, since Google has not put OpenCL into the official SDK.  Nonetheless, if you can avoid the vendor-specific extensions, then you can portable OpenCL code across different HW vendors.  Hopefully Google will support the standard, but they'll have to hold their nose at the affiliation it has with Apple (who holds the OpenCL trademark).

You can also accomplish a lot with traditional GPGPU computing in mobile.  We've done projects with that as well.

NVIDIA also talks about CUDA going onto Tegra at some point.  We look forward to seeing GPU computing on NVIDIA Tegra too.