I've been too occupied on other things to keep posting regularly in the last month. The good news is that I'm learning a lot about some new areas.
So what is new in hardware? I think there are some interesting trends in server hardware for running databases. The cost base of a mid-sized Solaris/Oracle server with 32-64GB of RAM is dropping fast. A very common platform in this space has been the 8-way UltraSPARC III based V880, moving to the 12-way V1280 and currently the E2900 (a 24 core V1280 chassis with UltraSPARC IV) over the last few years. Prices vary by configuration, and newer systems give you more performance per $, but are of the order of magnitude of $100K (plus the disk subsystem and software licenses - but thats another topic).
The two new entrants in this space are Niagara based systems and Opteron based systems, each has its strengths. When loaded up with RAM the costs are largely dominated by the price of RAM rather than the CPU itself, however both these systems use commonly available DIMMs, rather than the more specialized and expensive memory of the older generation systems.
Niagara has everything on one chip, 8 cores and 32 execution threads. The cool thing about this for database is not the low power consumption touted by Sun (which is dwarfed by the disk subsystem for a database application) , but is that any inter-thread locking will be blindingly fast since the signals do not have to go off-chip. Badly behaved applications that are sensitive to high memory latency (the kind that don't scale well on physically bigger systems) will run relatively well. However the cores themselves are not particularly fast and are atrociously slow for anything that does floating point, so single stream performance is not a strength. With 2GB DIMMs you can get 32GB RAM connected to a single Niagara chip, this should move to 64GB using 4GB DIMMs eventually. The performance of a Niagara seems to be a bit better than a V1280, but the cost is much much lower. Software support for SPARC Solaris 10 doesn't seem to be an issue at this point. Most things are supported and the system is compatible with earlier releases of SPARC/Solaris products.
The common Opteron systems are two socket/four core with a maximum of 16GB with 2GB DIMMs. There are some four socket and eight socket systems available from several vendors (including Sun), with 32-64GB, moving to 128GB with 4GB DIMMs. The Opteron seems to have performance per GHz in the same ballpark as UltraSPARC systems, so 8 cores at 2.4GHz would be between the performance of a V1280 and E2900. The 32GB 8-Core Opteron systems are in the same order of magnitude for performance and price as a 32GB Niagara, but far faster for single stream work and floating point, and relatively slower for lock intensive workloads where the signals have to move between the Opteron chips. On Opteron the software situation is a little different, there are three possible operating systems - Solaris 10, Linux and Windows 64. Solaris support isn't as good as it is on SPARC, for example Oracle 10g is the only option, the earlier releases of Oracle don't seem to be available. Linux probably has the widest choice for support, but 64bit Linux on larger systems doesn't seem to scale as well as Solaris 10 in my experience. Linux tends to be more efficient than Solaris on 32bit systems (your milage will vary, it depends greatly on what features of the OS your workload hits hard). I don't know anything about Windows 64, but I expect these large Opteron systems will be good SQLserver platforms.
Thats what the landscape looks like to me as we go into 2006. I hope to be doing some testing later this year to compare all the options, including Intel's next generation servers, to get my performance and price comparisons to be more precise than the general comments above. I'd be interested to swap experiences with other people moving in this direction.