PCMark Vantage does a great job of summarizing system performance, but I thought I'd pick a couple of applications to showcase real world strengths/weaknesses of these drives.
The first test is our Photoshop CS4 benchmark by the Retouch Artists. I made one small change to the way this test is run however. Normally I set the number of history states in Photoshop to 1, this significantly reduces the impact of the HDD/SSD on the test and makes it a better measure of CPU/memory speed. Since this is an SSD article, I've left the setting at its default value of 20. The numbers are now a lot lower and the performance a lot more disk bound.

I didn't run all of the drives through this test, just one from each major controller. The results speak for themselves. The Indilinx drives are actually the fastest MLC drives here. Even the Samsung is faster than the Intel drives in this test. Why? Sequential write speed. Even the VelociRaptor has a higher sequential write speed than the X25-M. So while sequential write speed isn't the most important metric to look at when evaluating an SSD, there are real world situations where it does matter.
Intel's performance here is just embarassing. Sequential write speed is something Intel needs to take more seriously in the future. Throw in any amount of random read/write operations alongside your Photoshop usage and the Intel drives would redeem themselves, but this is a very realistic snapshot of their achilles' heel.
Many of you have been asking for compiler benchmarks so I did just that. I grabbed the latest source for Pidgin (a popular IM application) and followed the developer's instructions on building it in Windows:

Nada. I thought perhaps it wasn't stressful enough so I tried building two instances in parallel:

And...nothing. It seems that building Pidgin is more CPU than IO bound, or at least its IO access isn't random enough to really benefit from an SSD. I'll keep experimenting with other compiler tests but this one appears to be a bust for SSD/HDD performance testing.
just to add to the chorus of praise: this is a superbly informative article, thank you for all the effort, and I hope that it has paid off for you, as I'm sure it must have.
My first question is this. Is it possible to analyse a program while you're using it, to see whether it is primarily doing sequential or random writes? Since there seems to be a quite clear difference between the Intel X25m 80gb and the OCZ vertex 120gb, which are the natural entry-level drives here, where the Intel works better for random access, the vertex for sequential, it would be very useful to know which I would make best use of.
Second question: does anyone know whether lightroom in particular is based around random or sequential writes? I know that a LR catalog is always radically fragmented, which suggests presumably that it is based around random writes, but that's just an uninformed guess. It does have a cache function, which produces files in the region of 3-5mb in size--are they likely to be sequential?
Third question: with photoshop, is it specifically as a scratch disk that the intel x25m underperforms? Or does photoshop do other sequential writes, besides those to the scratch disk? I ask because if it only doesn't work as a scratch disk, then that's not a big problem--anyone using this in a PC is likely to have a decent regular HDD for data anyway, so the scratch disk can just be sent there. In fact, I've been using a vertex 120gb, with a samsung spinpoint f3 500gb on my PC, and I found that with the scratch disk on the samsung I got better retouch artists results (only by about half a second, but that's out of 14 seconds, so still fairly significant).
Thanks in advance to anyone who might be able to answer, and thanks again Anand for such an informative read.
Cheers
Seth