The U.S. financial markets were closed, but a few analysts took a break from their Martin Luther King Day remembrances to say a few words about what Steve Jobs’ latest health advisory might mean to Apple (AAPL) shareholders.

Morgan Stanley’s Katy Huberty saw it as a “buying oppty ahead of earnings.”

Piper Jaffray’s Gene Munster treated it as a nonevent:

“Recall that during Jobs’ last medical leave (Jan-09 to Jun-09) Cook became interim CEO of Apple and the business continued to perform well. Since Jobs is not stepping down as CEO, we believe Jobs expects the leave to be shorter and/or less serious than his previous leave.”

RBC Capital’s Mike Abramsky took it more seriously, issuing big red “negative” trading indicator. He had three thoughts:

1) Limited disclosure (no indication of reason or seriousness or timing) may sustain uncertainty, including fears that Steve might not return this time (note last time Steve stepped down he specifically indicated he’d return in 6 months, but not this time).

2) That being said, investors may focus on the fact that Steve returned from 2 prior health absences successfully, and may observe (a) Apple has an otherwise strong management team and talented workforce with Tim Cook as operational leader; (b) Apple has a lengthy product pipeline and enormous sustained advantages which are likely to continue to sustain its business and leadership; (c) last time stock fell 3% on the day of the announcement only to subsequently rise 57% in the first 6 months of 2009 even with continued uncertainty and despite lack of news over Steve’s health and long-term status at Apple (however, note that at that time the stock was already depressed on rumors over Steve’s health and economic headwinds).

3) In our initiation we commented regarding Steve Jobs as being Apple’s biggest asset — and its biggest risk.  Upon his return he presided over the launch of iPhone 4, the iPad, the refresh of the Mac Air and other innovations.  It will be difficult to assess how the absence of Steve’s drive, innovation and leadership — and his high level of involvement — may or not have a negative impact in the longer term on Apple innovation and talent retention.  After handwringing, street and media reaction are likely to assume the stance for now that Apple can carry on.

UPDATE: Tuesday morning, Needham’s Charlie Wolf added this:

• As arguably the greatest innovator in the past century, Jobs has successively disrupted and redefined a series of industries, starting with the iPod in 2001, the iPhone in 2007 and most recently, the iPad in 2010.

• What Apple loses, then, in Jobs absence is the ability to redefine markets and industries going forward—in short, the option value of future innovations.

• We continue to recommend the stock. Apple’s shares were relatively inexpensive even before the latest news. More importantly, Apple has one of the deepest managerial benches in this country starting with Tim Cook. Jobs’ absence should have no material impact on Apple’s financial performance over the next several years.

• The major risk in the Apple story is Steve Jobs’ heath. Risks arising from the competitive landscape pale in comparison.

For comments from analysts about COO Tim Cook as interim chief, see here.

See also:

• Steve Jobs takes another medical leave
• Thinking the unthinkable: Apple without Steve Jobs
• Apple falls 9.7% in Frankfurt

[Follow Philip Elmer-DeWitt on Twitter @philiped]