“2008 is starting with a bang for open source,” wrote Mark Radcliffe last week, and he’s not wrong. Not only did we see Sun’s $1bn acquisition of MySQL, but we’ve also seen an extraordinary amount of venture capital funding. Today saw no fewer than three investments announced, with Greenplum landing $27m Series C, Zenoss closing a $11m Series B round, and Alfresco announcing a $9m Series C round.

According to 451 CAOS Theory figures $80.5m worth of open source VC funding has been announced in the first 22 days of 2008, compared with $100.4m in the whole of the first quarter of 2007. It’s an extraordinary turnaround after a dismal fourth quarter of 2008, and helps to explain why the funding level for the last quarter was so low. Clearly a few vendors were waiting until the New Year to make their announcements.

For the record, 2008’s open source funding deals break down as follows:

• Greenplum’s $27m from Meritech Capital Partners, Sun Microsystems, SAP Ventures
• Zenoss’s $11m from Grotech Capital Group, Intersouth Partners, Boulder Ventures, and the Maryland Department of Business and Economic Development.
• Alfresco’s $9m from SAP Ventures, Accel Partners and Mayfield Fund.
• Engine Yard’s $3.5m Series A from Benchmark.
• Openads’ $15.5m Series B from Accel Partners, Index Ventures, First Round Capital, Mangrove Capital Partners and O’Reilly AlphaTech Ventures.
• SugarCRM’s $14.5m Series D from Draper Fisher Jurvetson, New Enterprise Associates and Walden International.
• Additionally, First International Computer said it was providing capital for the spun-off OpenMoko.

It’s interesting, incidentally, to see SAP Ventures involved in both the Greenplum and Alfresco deals, while Sun’s investment in the PostgreSQL-based Greenplum in part backs up its commitment to the open source database project following its acquisition of MySQL. Sun was already a Greenplum partner.

The level of funding so far in 2008 also explains why some in the industry are still buoyant about open source investment levels despite the 40% drop in funding noted in 2007. So does the level of activity so far this year suggest we’ll see a significant revival in 2008? Personally I think the level of funding will even itself out over the year, but we’ll see perhaps a slight increase over 2007.

(Then again, it’s just possible, as Matt Asay notes, that open source vendors are getting their funding in now before the downturn hits).

Another potentially good sign for open source investment came from Index Ventures’ announcement that it has closed the €400m ($529m) million Index Ventures Growth I L.P fund, “formed to address the market opportunity created by the maturation of Europe’s start-up industry and the movement of traditional late-stage investors into larger deal sizes in both the technology and life science sectors.”

Index has previously been a big supporter of open source, and should be inclined towards further investment seeing as it just got a big fat pay-out from the MySQL deal. Additionally Scale Venture Partners, which is a JasperSoft investor, has declared its intention to do more open source deals.

Meanwhile, 451 CAOS Theory is aware of at least one further open source funding deal for which announcement is imminent. Also, while Sun’s acquisition of MySQL denied the industry one open source IPO this year, we should still expect to see at least one public offering before the year is out.

It’s going to be an interesting year.