A site I run has 6 sitelinks in Google search results.
I recently updated all the meta descriptions for the pages that sitelinks are provided for to give better summary text for each link. I then ensured Google re-indexed the site via Webmaster Tools.
Using site:mydomain.com to check the most recently cached version of each page, I can also see that when listed individually, the links to these pages have a description in Google's results corresponding to the updated meta description. However, in the sitelinks it is still the same text description as was there before I updated the meta tags. I can't understand why this is happening if Google has a more recent cache of those pages, I expected to see both the sitelink description and traditional search result description of the same page update at the time of re-indexing?