S3 Graphics has really fallen off the radar for years in terms of putting out new compelling products, their latest Chrome graphics cards are low-powered and do have some Linux drivers available, but the hardware itself is hard to find and is not superior to the low-end offerings from AMD and NVIDIA.
What S3 has, however, is a decent graphics IP portfolio that HTC can use to design better mobile graphics solutions for their devices. In particular, the biggest asset of S3 is their S3 Texture Compression patent, which they have licensed to all of the other major graphics vendors.
It's also the S3TC patent that makes things a mess for open-source graphics drivers in implementing this widely-used texture compression technique. It would be lovely if HTC would end up "freeing" the S3 Texture Compression for open-source use, but chances of that happening are slim as this is still really S3's greatest piece of IP. At least though it's leaving VIA's hands.