Yesterday's Wall Street Journal Top 50 Startups list, identifying the publication's guess at the most promising startups in the U.S., listed out last year's IPOs from its crop of companies--topped by Fusion-io, the now public maker of solid state storage. Fusion-io, based in Utah, was one of six companies in last year's list which made it to the public markets. Only two of those were from Silicon Valley. That highlights one of the region's strengths, which has been a high rate of IPO exits, particularly given a far smaller venture funding base than places like Silicon Valley. The rate of IPO filings--examples being LifeLock (Tempe, recently filed), Gogo (Boulder operations, filed in Dec of 2011), Clovis Oncology (IPO in November 2011), Rally Software (rumored to be in the process of an IPO filing), Skullcandy (IPO in July 2011), and Gevo (IPO, February 2011)--appear to be at a much greater rate than the volume and size of venture fundings might suggest for the region.