Samsung has just introduced a very small format PC, in the UMPC category (ultra mobile PC) that eschews a hard drive for 32GB of Samsung flash memory. That's double the amount found on a Sony Vaio flash-based UMPC introduced a few months ago. Samsung says users get better performance than the Vaio, better performance than a hard-drive-based UMPC and also extended battery life, Roses all round ... but ....
Flash memory has a limited read-write cycle capacity. An Imation web site page says it's between 10,000 and 100,000 read-write cycles. I guess that's to a particular cell. But consider Windows XP; it's a real disk thrasher. If we simply replace a hard drive with a flash drive on a Windows XP system then the flash is going to get hammered. These things are going to have to have some kind of extended read-write cycle capacity guarantee.
Another little gotcha is fragmentation. There will need, I'm convinced, to be defragmentation runs to put back together again all the fragmented files that occur as the flash memory has differently sized files added to it, deleted, extended and decreased in size. As this happens fragmented file read performance lengthens.
The very process that puts this right - defragmentation - adds to the cumulative read-write cycle total for the flash memory. Unless these concerns are addressed then a flash UMPC could have a rather shorter usable life than supposed.