Can work, but depends on the speeds of the card (just because it's class 10 for continuous sequential data, doesn't mean it will be good enough for the tricky 4k reads), and on the performance of the built-in reader.
My laptop (Netbook) does accept the SD as usable for readyboost.
The Sandisk Ultra or Extreme usually do ok, take a look at some speed checks in "the slug race II"
NB. With FAT32 card format, a maximum of 4GB is usable for readyboost - reformatting to NTFS or exFAT would allow the full capacity to be used.