Bill Hartzer has started a thread at WebmasterWorld suggesting that Google is speeding up the rate at which it is indexing new content. Bill reports a post that he did in his blog showing up in the index in 5 to 6 hours.
Brett Tabke then chips in with a page that he just added to WebmasterWorld, noting it took less than 5 hours to show up in the index. Barry Schwartz also comments on the thread, suggesting that this is not particularly new.
Note that all the examples offered of pages that were added to well known and thoroughly indexed sites. Your mileage may very depending on where your site is in the indexing process, and also that of establishing trust with Google.
In addition, all examples are of sites that are blog and/or forum based. I suspect that the combination of the existing trust, and the knowledge that the content on these sites is constantly changing is causing Google to look at these sites with much greater frequency than the norm. Therefore, I wouldn't expect this faster indexing to hold true for other types of sites.