I'm not asking whether or not it's worth the money, as in Question 2425. I'm interested to see the level of acceptance in the production world up to now. Money can certainly relate to the answer, but it would be why you do or do not use SSD at this time.
I don't. I'm not actually concerned about the rewrite issue since the write-life of modern SSD drives is long enough that it's sure to die from other causes before you hit it.
I don't use them because they're the bleeding edge of technology, and I have no services that are so disk read-/write-speed bound that I can justify the additional risk of relatively untested hardware.
My general policy is that if I have to install the piece of hardware myself and it's not necessary for a very particular case (e.g., installing a Digium PRI card for an Asterisk server), that hardware isn't mature enough for my needs.
I'll consider installing them on my routers, load balancers, and web servers when Dell ships servers with SSDs already installed by default.
The only suitable product is the PCI-E cards from FusionIO. They can sustain fast writes indefinately (although you have to consider increasing the amount of "reserved" space). I wrote to several non-stop for a several-month period and the number of bad blocks did not grow appreciably - it should last at least for years under a non-stop write load. This supports the manufacturer's claims.
No other SSD product that I encountered has fast write performance at all. No other SSD product that I encountered exposes the number of bad blocks so that you can verify that you are not wearing the card out prematurely.
Beware that the tricks that the FusionIO cards employ to allow fast writes require you to increase the reserved space if your workload is write-intensive.
They have very fast read performance, always.
A pair of mirrored FusionIO cards replaced a multi-hundred-thousand dollar SAN solution for a critical database for me. This was on a trading-related database when the stock market went crazy in August. Our systems would have been crippled without these cards, and instead there was no significant performance concern.
Not SSD's per se, but we used Fusion IO in our search engine product. Blazing fast for us and remove all kinds of I/O bottlenecks. Products like Fusion IO should rapidly replace huge SANs in the next 5 years or so.
We used the Fusion IO products since early alpha, and they've improved with each revision. Quality stuff.